Class: _

_(value) → {Object}

new _(value) → {Object}

Creates a `lodash` object which wraps `value` to enable implicit method chain sequences. Methods that operate on and return arrays, collections, and functions can be chained together. Methods that retrieve a single value or may return a primitive value will automatically end the chain sequence and return the unwrapped value. Otherwise, the value must be unwrapped with `_#value`. Explicit chain sequences, which must be unwrapped with `_#value`, may be enabled using `_.chain`. The execution of chained methods is lazy, that is, it's deferred until `_#value` is implicitly or explicitly called. Lazy evaluation allows several methods to support shortcut fusion. Shortcut fusion is an optimization to merge iteratee calls; this avoids the creation of intermediate arrays and can greatly reduce the number of iteratee executions. Sections of a chain sequence qualify for shortcut fusion if the section is applied to an array and iteratees accept only one argument. The heuristic for whether a section qualifies for shortcut fusion is subject to change. Chaining is supported in custom builds as long as the `_#value` method is directly or indirectly included in the build. In addition to lodash methods, wrappers have `Array` and `String` methods. The wrapper `Array` methods are: `concat`, `join`, `pop`, `push`, `shift`, `sort`, `splice`, and `unshift` The wrapper `String` methods are: `replace` and `split` The wrapper methods that support shortcut fusion are: `at`, `compact`, `drop`, `dropRight`, `dropWhile`, `filter`, `find`, `findLast`, `head`, `initial`, `last`, `map`, `reject`, `reverse`, `slice`, `tail`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, and `toArray` The chainable wrapper methods are: `after`, `ary`, `assign`, `assignIn`, `assignInWith`, `assignWith`, `at`, `before`, `bind`, `bindAll`, `bindKey`, `castArray`, `chain`, `chunk`, `commit`, `compact`, `concat`, `conforms`, `constant`, `countBy`, `create`, `curry`, `debounce`, `defaults`, `defaultsDeep`, `defer`, `delay`, `difference`, `differenceBy`, `differenceWith`, `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `extend`, `extendWith`, `fill`, `filter`, `flatMap`, `flatMapDeep`, `flatMapDepth`, `flatten`, `flattenDeep`, `flattenDepth`, `flip`, `flow`, `flowRight`, `fromPairs`, `functions`, `functionsIn`, `groupBy`, `initial`, `intersection`, `intersectionBy`, `intersectionWith`, `invert`, `invertBy`, `invokeMap`, `iteratee`, `keyBy`, `keys`, `keysIn`, `map`, `mapKeys`, `mapValues`, `matches`, `matchesProperty`, `memoize`, `merge`, `mergeWith`, `method`, `methodOf`, `mixin`, `negate`, `nthArg`, `omit`, `omitBy`, `once`, `orderBy`, `over`, `overArgs`, `overEvery`, `overSome`, `partial`, `partialRight`, `partition`, `pick`, `pickBy`, `plant`, `property`, `propertyOf`, `pull`, `pullAll`, `pullAllBy`, `pullAllWith`, `pullAt`, `push`, `range`, `rangeRight`, `rearg`, `reject`, `remove`, `rest`, `reverse`, `sampleSize`, `set`, `setWith`, `shuffle`, `slice`, `sort`, `sortBy`, `splice`, `spread`, `tail`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, `tap`, `throttle`, `thru`, `toArray`, `toPairs`, `toPairsIn`, `toPath`, `toPlainObject`, `transform`, `unary`, `union`, `unionBy`, `unionWith`, `uniq`, `uniqBy`, `uniqWith`, `unset`, `unshift`, `unzip`, `unzipWith`, `update`, `updateWith`, `values`, `valuesIn`, `without`, `wrap`, `xor`, `xorBy`, `xorWith`, `zip`, `zipObject`, `zipObjectDeep`, and `zipWith` The wrapper methods that are **not** chainable by default are: `add`, `attempt`, `camelCase`, `capitalize`, `ceil`, `clamp`, `clone`, `cloneDeep`, `cloneDeepWith`, `cloneWith`, `conformsTo`, `deburr`, `defaultTo`, `divide`, `each`, `eachRight`, `endsWith`, `eq`, `escape`, `escapeRegExp`, `every`, `find`, `findIndex`, `findKey`, `findLast`, `findLastIndex`, `findLastKey`, `first`, `floor`, `forEach`, `forEachRight`, `forIn`, `forInRight`, `forOwn`, `forOwnRight`, `get`, `gt`, `gte`, `has`, `hasIn`, `head`, `identity`, `includes`, `indexOf`, `inRange`, `invoke`, `isArguments`, `isArray`, `isArrayBuffer`, `isArrayLike`, `isArrayLikeObject`, `isBoolean`, `isBuffer`, `isDate`, `isElement`, `isEmpty`, `isEqual`, `isEqualWith`, `isError`, `isFinite`, `isFunction`, `isInteger`, `isLength`, `isMap`, `isMatch`, `isMatchWith`, `isNaN`, `isNative`, `isNil`, `isNull`, `isNumber`, `isObject`, `isObjectLike`, `isPlainObject`, `isRegExp`, `isSafeInteger`, `isSet`, `isString`, `isUndefined`, `isTypedArray`, `isWeakMap`, `isWeakSet`, `join`, `kebabCase`, `last`, `lastIndexOf`, `lowerCase`, `lowerFirst`, `lt`, `lte`, `max`, `maxBy`, `mean`, `meanBy`, `min`, `minBy`, `multiply`, `noConflict`, `noop`, `now`, `nth`, `pad`, `padEnd`, `padStart`, `parseInt`, `pop`, `random`, `reduce`, `reduceRight`, `repeat`, `result`, `round`, `runInContext`, `sample`, `shift`, `size`, `snakeCase`, `some`, `sortedIndex`, `sortedIndexBy`, `sortedLastIndex`, `sortedLastIndexBy`, `startCase`, `startsWith`, `stubArray`, `stubFalse`, `stubObject`, `stubString`, `stubTrue`, `subtract`, `sum`, `sumBy`, `template`, `times`, `toFinite`, `toInteger`, `toJSON`, `toLength`, `toLower`, `toNumber`, `toSafeInteger`, `toString`, `toUpper`, `trim`, `trimEnd`, `trimStart`, `truncate`, `unescape`, `uniqueId`, `upperCase`, `upperFirst`, `value`, and `words`
Parameters:
Name Type Description
value * The value to wrap in a `lodash` instance.
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2, 3]);

// Returns an unwrapped value.
wrapped.reduce(_.add);
// => 6

// Returns a wrapped value.
var squares = wrapped.map(square);

_.isArray(squares);
// => false

_.isArray(squares.value());
// => true

Members

(static) add

Adds two numbers.
Since:
  • 3.4.0
Source:
Example
_.add(6, 4);
// => 10

(static) add

Adds two numbers.
Since:
  • 3.4.0
Source:
Example
_.add(6, 4);
// => 10

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assignWith

This method is like `_.assign` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
  • _.assignInWith
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) assignWith

This method is like `_.assign` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
  • _.assignInWith
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) at

Creates an array of values corresponding to `paths` of `object`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_.at(object, ['a[0].b.c', 'a[1]']);
// => [3, 4]

(static) at

This method is the wrapper version of `_.at`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]

(static) at

Creates an array of values corresponding to `paths` of `object`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_.at(object, ['a[0].b.c', 'a[1]']);
// => [3, 4]

(static) at

This method is the wrapper version of `_.at`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]

(static) attempt

Attempts to invoke `func`, returning either the result or the caught error object. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 3.0.0
Source:
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
  return document.querySelectorAll(selector);
}, '>_>');

if (_.isError(elements)) {
  elements = [];
}

(static) attempt

Attempts to invoke `func`, returning either the result or the caught error object. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 3.0.0
Source:
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
  return document.querySelectorAll(selector);
}, '>_>');

if (_.isError(elements)) {
  elements = [];
}

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bindAll

Binds methods of an object to the object itself, overwriting the existing method. **Note:** This method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
var view = {
  'label': 'docs',
  'click': function() {
    console.log('clicked ' + this.label);
  }
};

_.bindAll(view, ['click']);
jQuery(element).on('click', view.click);
// => Logs 'clicked docs' when clicked.

(static) bindAll

Binds methods of an object to the object itself, overwriting the existing method. **Note:** This method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
var view = {
  'label': 'docs',
  'click': function() {
    console.log('clicked ' + this.label);
  }
};

_.bindAll(view, ['click']);
jQuery(element).on('click', view.click);
// => Logs 'clicked docs' when clicked.

(static) bindKey

Creates a function that invokes the method at `object[key]` with `partials` prepended to the arguments it receives. This method differs from `_.bind` by allowing bound functions to reference methods that may be redefined or don't yet exist. See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern) for more details. The `_.bindKey.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments.
Since:
  • 0.10.0
Source:
Example
var object = {
  'user': 'fred',
  'greet': function(greeting, punctuation) {
    return greeting + ' ' + this.user + punctuation;
  }
};

var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// => 'hi fred!'

object.greet = function(greeting, punctuation) {
  return greeting + 'ya ' + this.user + punctuation;
};

bound('!');
// => 'hiya fred!'

// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// => 'hiya fred!'

(static) bindKey

Creates a function that invokes the method at `object[key]` with `partials` prepended to the arguments it receives. This method differs from `_.bind` by allowing bound functions to reference methods that may be redefined or don't yet exist. See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern) for more details. The `_.bindKey.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments.
Since:
  • 0.10.0
Source:
Example
var object = {
  'user': 'fred',
  'greet': function(greeting, punctuation) {
    return greeting + ' ' + this.user + punctuation;
  }
};

var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// => 'hi fred!'

object.greet = function(greeting, punctuation) {
  return greeting + 'ya ' + this.user + punctuation;
};

bound('!');
// => 'hiya fred!'

// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// => 'hiya fred!'

(static) camelCase

Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
Since:
  • 3.0.0
Source:
Example
_.camelCase('Foo Bar');
// => 'fooBar'

_.camelCase('--foo-bar--');
// => 'fooBar'

_.camelCase('__FOO_BAR__');
// => 'fooBar'

(static) camelCase

Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
Since:
  • 3.0.0
Source:
Example
_.camelCase('Foo Bar');
// => 'fooBar'

_.camelCase('--foo-bar--');
// => 'fooBar'

_.camelCase('__FOO_BAR__');
// => 'fooBar'

(static) ceil

Computes `number` rounded up to `precision`.
Since:
  • 3.10.0
Source:
Example
_.ceil(4.006);
// => 5

_.ceil(6.004, 2);
// => 6.01

_.ceil(6040, -2);
// => 6100

(static) ceil

Computes `number` rounded up to `precision`.
Since:
  • 3.10.0
Source:
Example
_.ceil(4.006);
// => 5

_.ceil(6.004, 2);
// => 6.01

_.ceil(6040, -2);
// => 6100

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) commit

Executes the chain sequence and returns the wrapped result.
Since:
  • 3.2.0
Source:
Example
var array = [1, 2];
var wrapped = _(array).push(3);

console.log(array);
// => [1, 2]

wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]

wrapped.last();
// => 3

console.log(array);
// => [1, 2, 3]

(static) commit

Executes the chain sequence and returns the wrapped result.
Since:
  • 3.2.0
Source:
Example
var array = [1, 2];
var wrapped = _(array).push(3);

console.log(array);
// => [1, 2]

wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]

wrapped.last();
// => 3

console.log(array);
// => [1, 2, 3]

(static) countBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the number of times the key was returned by `iteratee`. The iteratee is invoked with one argument: (value).
Since:
  • 0.5.0
Source:
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }

// The `_.property` iteratee shorthand.
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }

(static) countBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the number of times the key was returned by `iteratee`. The iteratee is invoked with one argument: (value).
Since:
  • 0.5.0
Source:
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }

// The `_.property` iteratee shorthand.
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaultsDeep

This method is like `_.defaults` except that it recursively assigns default properties. **Note:** This method mutates `object`.
Since:
  • 3.10.0
Source:
See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } });
// => { 'a': { 'b': 2, 'c': 3 } }

(static) defaultsDeep

This method is like `_.defaults` except that it recursively assigns default properties. **Note:** This method mutates `object`.
Since:
  • 3.10.0
Source:
See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } });
// => { 'a': { 'b': 2, 'c': 3 } }

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) difference

Creates an array of `array` values not included in the other given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array. **Note:** Unlike `_.pullAll`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.without, _.xor
Example
_.difference([2, 1], [2, 3]);
// => [1]

(static) difference

Creates an array of `array` values not included in the other given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array. **Note:** Unlike `_.pullAll`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.without, _.xor
Example
_.difference([2, 1], [2, 3]);
// => [1]

(static) differenceBy

This method is like `_.difference` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.pullAllBy`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2]

// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) differenceBy

This method is like `_.difference` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.pullAllBy`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2]

// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) differenceWith

This method is like `_.difference` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.pullAllWith`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];

_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

(static) differenceWith

This method is like `_.difference` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.pullAllWith`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];

_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

(static) divide

Divide two numbers.
Since:
  • 4.7.0
Source:
Example
_.divide(6, 4);
// => 1.5

(static) divide

Divide two numbers.
Since:
  • 4.7.0
Source:
Example
_.divide(6, 4);
// => 1.5

(static) entries

Creates an array of own enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)

(static) entries

Creates an array of own enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)

(static) entriesIn

Creates an array of own and inherited enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)

(static) entriesIn

Creates an array of own and inherited enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extendWith

This method is like `_.assignIn` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignInWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) extendWith

This method is like `_.assignIn` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignInWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) findLast

This method is like `_.find` except that it iterates over elements of `collection` from right to left.
Since:
  • 2.0.0
Source:
Example
_.findLast([1, 2, 3, 4], function(n) {
  return n % 2 == 1;
});
// => 3

(static) findLast

This method is like `_.find` except that it iterates over elements of `collection` from right to left.
Since:
  • 2.0.0
Source:
Example
_.findLast([1, 2, 3, 4], function(n) {
  return n % 2 == 1;
});
// => 3

(static) floor

Computes `number` rounded down to `precision`.
Since:
  • 3.10.0
Source:
Example
_.floor(4.006);
// => 4

_.floor(0.046, 2);
// => 0.04

_.floor(4060, -2);
// => 4000

(static) floor

Computes `number` rounded down to `precision`.
Since:
  • 3.10.0
Source:
Example
_.floor(4.006);
// => 4

_.floor(0.046, 2);
// => 0.04

_.floor(4060, -2);
// => 4000

(static) flow

Creates a function that returns the result of invoking the given functions with the `this` binding of the created function, where each successive invocation is supplied the return value of the previous.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flow([_.add, square]);
addSquare(1, 2);
// => 9

(static) flow

Creates a function that returns the result of invoking the given functions with the `this` binding of the created function, where each successive invocation is supplied the return value of the previous.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flow([_.add, square]);
addSquare(1, 2);
// => 9

(static) flowRight

This method is like `_.flow` except that it creates a function that invokes the given functions from right to left.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flowRight([square, _.add]);
addSquare(1, 2);
// => 9

(static) flowRight

This method is like `_.flow` except that it creates a function that invokes the given functions from right to left.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flowRight([square, _.add]);
addSquare(1, 2);
// => 9

(static) groupBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }

// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

(static) groupBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }

// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

(static) gt

Checks if `value` is greater than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gt(3, 1);
// => true

_.gt(3, 3);
// => false

_.gt(1, 3);
// => false

(static) gt

Checks if `value` is greater than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gt(3, 1);
// => true

_.gt(3, 3);
// => false

_.gt(1, 3);
// => false

(static) gte

Checks if `value` is greater than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gte(3, 1);
// => true

_.gte(3, 3);
// => true

_.gte(1, 3);
// => false

(static) gte

Checks if `value` is greater than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gte(3, 1);
// => true

_.gte(3, 3);
// => true

_.gte(1, 3);
// => false

(static) intersection

Creates an array of unique values that are included in all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array.
Since:
  • 0.1.0
Source:
Example
_.intersection([2, 1], [2, 3]);
// => [2]

(static) intersection

Creates an array of unique values that are included in all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array.
Since:
  • 0.1.0
Source:
Example
_.intersection([2, 1], [2, 3]);
// => [2]

(static) intersectionBy

This method is like `_.intersection` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [2.1]

// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }]

(static) intersectionBy

This method is like `_.intersection` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [2.1]

// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }]

(static) intersectionWith

This method is like `_.intersection` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.intersectionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }]

(static) intersectionWith

This method is like `_.intersection` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.intersectionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }]

(static) invert

Creates an object composed of the inverted keys and values of `object`. If `object` contains duplicate values, subsequent values overwrite property assignments of previous values.
Since:
  • 0.7.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invert(object);
// => { '1': 'c', '2': 'b' }

(static) invert

Creates an object composed of the inverted keys and values of `object`. If `object` contains duplicate values, subsequent values overwrite property assignments of previous values.
Since:
  • 0.7.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invert(object);
// => { '1': 'c', '2': 'b' }

(static) invertBy

This method is like `_.invert` except that the inverted object is generated from the results of running each element of `object` thru `iteratee`. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. The iteratee is invoked with one argument: (value).
Since:
  • 4.1.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }

_.invertBy(object, function(value) {
  return 'group' + value;
});
// => { 'group1': ['a', 'c'], 'group2': ['b'] }

(static) invertBy

This method is like `_.invert` except that the inverted object is generated from the results of running each element of `object` thru `iteratee`. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. The iteratee is invoked with one argument: (value).
Since:
  • 4.1.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }

_.invertBy(object, function(value) {
  return 'group' + value;
});
// => { 'group1': ['a', 'c'], 'group2': ['b'] }

(static) invoke

Invokes the method at `path` of `object`.
Since:
  • 4.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };

_.invoke(object, 'a[0].b.c.slice', 1, 3);
// => [2, 3]

(static) invoke

Invokes the method at `path` of `object`.
Since:
  • 4.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };

_.invoke(object, 'a[0].b.c.slice', 1, 3);
// => [2, 3]

(static) invokeMap

Invokes the method at `path` of each element in `collection`, returning an array of the results of each invoked method. Any additional arguments are provided to each invoked method. If `path` is a function, it's invoked for, and `this` bound to, each element in `collection`.
Since:
  • 4.0.0
Source:
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]

_.invokeMap([123, 456], String.prototype.split, '');
// => [['1', '2', '3'], ['4', '5', '6']]

(static) invokeMap

Invokes the method at `path` of each element in `collection`, returning an array of the results of each invoked method. Any additional arguments are provided to each invoked method. If `path` is a function, it's invoked for, and `this` bound to, each element in `collection`.
Since:
  • 4.0.0
Source:
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]

_.invokeMap([123, 456], String.prototype.split, '');
// => [['1', '2', '3'], ['4', '5', '6']]

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray :function

Checks if `value` is classified as an `Array` object.
Type:
  • function
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArrayBuffer

Checks if `value` is classified as an `ArrayBuffer` object.
Since:
  • 4.3.0
Source:
Example
_.isArrayBuffer(new ArrayBuffer(2));
// => true

_.isArrayBuffer(new Array(2));
// => false

(static) isArrayBuffer

Checks if `value` is classified as an `ArrayBuffer` object.
Since:
  • 4.3.0
Source:
Example
_.isArrayBuffer(new ArrayBuffer(2));
// => true

_.isArrayBuffer(new Array(2));
// => false

(static) isBuffer

Checks if `value` is a buffer.
Since:
  • 4.3.0
Source:
Example
_.isBuffer(new Buffer(2));
// => true

_.isBuffer(new Uint8Array(2));
// => false

(static) isBuffer

Checks if `value` is a buffer.
Since:
  • 4.3.0
Source:
Example
_.isBuffer(new Buffer(2));
// => true

_.isBuffer(new Uint8Array(2));
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isMap

Checks if `value` is classified as a `Map` object.
Since:
  • 4.3.0
Source:
Example
_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false

(static) isMap

Checks if `value` is classified as a `Map` object.
Since:
  • 4.3.0
Source:
Example
_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isSet

Checks if `value` is classified as a `Set` object.
Since:
  • 4.3.0
Source:
Example
_.isSet(new Set);
// => true

_.isSet(new WeakSet);
// => false

(static) isSet

Checks if `value` is classified as a `Set` object.
Since:
  • 4.3.0
Source:
Example
_.isSet(new Set);
// => true

_.isSet(new WeakSet);
// => false

(static) isTypedArray

Checks if `value` is classified as a typed array.
Since:
  • 3.0.0
Source:
Example
_.isTypedArray(new Uint8Array);
// => true

_.isTypedArray([]);
// => false

(static) isTypedArray

Checks if `value` is classified as a typed array.
Since:
  • 3.0.0
Source:
Example
_.isTypedArray(new Uint8Array);
// => true

_.isTypedArray([]);
// => false

(static) iteratee

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Since:
  • 4.0.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) kebabCase

Converts `string` to [kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).
Since:
  • 3.0.0
Source:
Example
_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'

(static) kebabCase

Converts `string` to [kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).
Since:
  • 3.0.0
Source:
Example
_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'

(static) keyBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the last element responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
var array = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

_.keyBy(array, function(o) {
  return String.fromCharCode(o.code);
});
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }

_.keyBy(array, 'dir');
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }

(static) keyBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the last element responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
var array = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

_.keyBy(array, function(o) {
  return String.fromCharCode(o.code);
});
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }

_.keyBy(array, 'dir');
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }

(static) keys

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Since:
  • 0.1.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keysIn

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Since:
  • 3.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) lowerCase

Converts `string`, as space separated words, to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerCase('--Foo-Bar--');
// => 'foo bar'

_.lowerCase('fooBar');
// => 'foo bar'

_.lowerCase('__FOO_BAR__');
// => 'foo bar'

(static) lowerCase

Converts `string`, as space separated words, to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerCase('--Foo-Bar--');
// => 'foo bar'

_.lowerCase('fooBar');
// => 'foo bar'

_.lowerCase('__FOO_BAR__');
// => 'foo bar'

(static) lowerFirst

Converts the first character of `string` to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

(static) lowerFirst

Converts the first character of `string` to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

(static) lt

Checks if `value` is less than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lt(1, 3);
// => true

_.lt(3, 3);
// => false

_.lt(3, 1);
// => false

(static) lt

Checks if `value` is less than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lt(1, 3);
// => true

_.lt(3, 3);
// => false

_.lt(3, 1);
// => false

(static) lte

Checks if `value` is less than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lte(1, 3);
// => true

_.lte(3, 3);
// => true

_.lte(3, 1);
// => false

(static) lte

Checks if `value` is less than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lte(1, 3);
// => true

_.lte(3, 3);
// => true

_.lte(3, 1);
// => false

(static) merge

This method is like `_.assign` except that it recursively merges own and inherited enumerable string keyed properties of source objects into the destination object. Source properties that resolve to `undefined` are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object`.
Since:
  • 0.5.0
Source:
Example
var object = {
  'a': [{ 'b': 2 }, { 'd': 4 }]
};

var other = {
  'a': [{ 'c': 3 }, { 'e': 5 }]
};

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }

(static) merge

This method is like `_.assign` except that it recursively merges own and inherited enumerable string keyed properties of source objects into the destination object. Source properties that resolve to `undefined` are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object`.
Since:
  • 0.5.0
Source:
Example
var object = {
  'a': [{ 'b': 2 }, { 'd': 4 }]
};

var other = {
  'a': [{ 'c': 3 }, { 'e': 5 }]
};

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }

(static) mergeWith

This method is like `_.merge` except that it accepts `customizer` which is invoked to produce the merged values of the destination and source properties. If `customizer` returns `undefined`, merging is handled by the method instead. The `customizer` is invoked with six arguments: (objValue, srcValue, key, object, source, stack). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
Example
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }

(static) mergeWith

This method is like `_.merge` except that it accepts `customizer` which is invoked to produce the merged values of the destination and source properties. If `customizer` returns `undefined`, merging is handled by the method instead. The `customizer` is invoked with six arguments: (objValue, srcValue, key, object, source, stack). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
Example
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }

(static) method

Creates a function that invokes the method at `path` of a given object. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var objects = [
  { 'a': { 'b': _.constant(2) } },
  { 'a': { 'b': _.constant(1) } }
];

_.map(objects, _.method('a.b'));
// => [2, 1]

_.map(objects, _.method(['a', 'b']));
// => [2, 1]

(static) method

Creates a function that invokes the method at `path` of a given object. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var objects = [
  { 'a': { 'b': _.constant(2) } },
  { 'a': { 'b': _.constant(1) } }
];

_.map(objects, _.method('a.b'));
// => [2, 1]

_.map(objects, _.method(['a', 'b']));
// => [2, 1]

(static) methodOf

The opposite of `_.method`; this method creates a function that invokes the method at a given path of `object`. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var array = _.times(3, _.constant),
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.methodOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// => [2, 0]

(static) methodOf

The opposite of `_.method`; this method creates a function that invokes the method at a given path of `object`. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var array = _.times(3, _.constant),
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.methodOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// => [2, 0]

(static) multiply

Multiply two numbers.
Since:
  • 4.7.0
Source:
Example
_.multiply(6, 4);
// => 24

(static) multiply

Multiply two numbers.
Since:
  • 4.7.0
Source:
Example
_.multiply(6, 4);
// => 24

(static) next

Gets the next value on a wrapped object following the [iterator protocol](https://mdn.io/iteration_protocols#iterator).
Since:
  • 4.0.0
Source:
Example
var wrapped = _([1, 2]);

wrapped.next();
// => { 'done': false, 'value': 1 }

wrapped.next();
// => { 'done': false, 'value': 2 }

wrapped.next();
// => { 'done': true, 'value': undefined }

(static) next

Gets the next value on a wrapped object following the [iterator protocol](https://mdn.io/iteration_protocols#iterator).
Since:
  • 4.0.0
Source:
Example
var wrapped = _([1, 2]);

wrapped.next();
// => { 'done': false, 'value': 1 }

wrapped.next();
// => { 'done': false, 'value': 2 }

wrapped.next();
// => { 'done': true, 'value': undefined }

(static) now

Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
Since:
  • 2.4.0
Source:
Example
_.defer(function(stamp) {
  console.log(_.now() - stamp);
}, _.now());
// => Logs the number of milliseconds it took for the deferred invocation.

(static) omit

The opposite of `_.pick`; this method creates an object composed of the own and inherited enumerable property paths of `object` that are not omitted. **Note:** This method is considerably slower than `_.pick`.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);
// => { 'b': '2' }

(static) omit

The opposite of `_.pick`; this method creates an object composed of the own and inherited enumerable property paths of `object` that are not omitted. **Note:** This method is considerably slower than `_.pick`.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);
// => { 'b': '2' }

(static) over

Creates a function that invokes `iteratees` with the arguments it receives and returns their results.
Since:
  • 4.0.0
Source:
Example
var func = _.over([Math.max, Math.min]);

func(1, 2, 3, 4);
// => [4, 1]

(static) over

Creates a function that invokes `iteratees` with the arguments it receives and returns their results.
Since:
  • 4.0.0
Source:
Example
var func = _.over([Math.max, Math.min]);

func(1, 2, 3, 4);
// => [4, 1]

(static) overArgs

Creates a function that invokes `func` with its arguments transformed.
Since:
  • 4.0.0
Source:
Example
function doubled(n) {
  return n * 2;
}

function square(n) {
  return n * n;
}

var func = _.overArgs(function(x, y) {
  return [x, y];
}, [square, doubled]);

func(9, 3);
// => [81, 6]

func(10, 5);
// => [100, 10]

(static) overArgs

Creates a function that invokes `func` with its arguments transformed.
Since:
  • 4.0.0
Source:
Example
function doubled(n) {
  return n * 2;
}

function square(n) {
  return n * n;
}

var func = _.overArgs(function(x, y) {
  return [x, y];
}, [square, doubled]);

func(9, 3);
// => [81, 6]

func(10, 5);
// => [100, 10]

(static) overEvery

Creates a function that checks if **all** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overEvery([Boolean, isFinite]);

func('1');
// => true

func(null);
// => false

func(NaN);
// => false

(static) overEvery

Creates a function that checks if **all** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overEvery([Boolean, isFinite]);

func('1');
// => true

func(null);
// => false

func(NaN);
// => false

(static) overSome

Creates a function that checks if **any** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overSome([Boolean, isFinite]);

func('1');
// => true

func(null);
// => true

func(NaN);
// => false

var matchesFunc = _.overSome([{ 'a': 1 }, { 'a': 2 }])
var matchesPropertyFunc = _.overSome([['a', 1], ['a', 2]])

(static) overSome

Creates a function that checks if **any** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overSome([Boolean, isFinite]);

func('1');
// => true

func(null);
// => true

func(NaN);
// => false

var matchesFunc = _.overSome([{ 'a': 1 }, { 'a': 2 }])
var matchesPropertyFunc = _.overSome([['a', 1], ['a', 2]])

(static) partial

Creates a function that invokes `func` with `partials` prepended to the arguments it receives. This method is like `_.bind` except it does **not** alter the `this` binding. The `_.partial.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 0.2.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'

// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'

(static) partial

Creates a function that invokes `func` with `partials` prepended to the arguments it receives. This method is like `_.bind` except it does **not** alter the `this` binding. The `_.partial.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 0.2.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'

// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'

(static) partialRight

This method is like `_.partial` except that partially applied arguments are appended to the arguments it receives. The `_.partialRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 1.0.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'

// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'

(static) partialRight

This method is like `_.partial` except that partially applied arguments are appended to the arguments it receives. The `_.partialRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 1.0.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'

// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'

(static) partition

Creates an array of elements split into two groups, the first of which contains elements `predicate` returns truthy for, the second of which contains elements `predicate` returns falsey for. The predicate is invoked with one argument: (value).
Since:
  • 3.0.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': false },
  { 'user': 'fred',    'age': 40, 'active': true },
  { 'user': 'pebbles', 'age': 1,  'active': false }
];

_.partition(users, function(o) { return o.active; });
// => objects for [['fred'], ['barney', 'pebbles']]

// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// => objects for [['pebbles'], ['barney', 'fred']]

// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// => objects for [['barney', 'pebbles'], ['fred']]

// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// => objects for [['fred'], ['barney', 'pebbles']]

(static) partition

Creates an array of elements split into two groups, the first of which contains elements `predicate` returns truthy for, the second of which contains elements `predicate` returns falsey for. The predicate is invoked with one argument: (value).
Since:
  • 3.0.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': false },
  { 'user': 'fred',    'age': 40, 'active': true },
  { 'user': 'pebbles', 'age': 1,  'active': false }
];

_.partition(users, function(o) { return o.active; });
// => objects for [['fred'], ['barney', 'pebbles']]

// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// => objects for [['pebbles'], ['barney', 'fred']]

// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// => objects for [['barney', 'pebbles'], ['fred']]

// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// => objects for [['fred'], ['barney', 'pebbles']]

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) plant

Creates a clone of the chain sequence planting `value` as the wrapped value.
Since:
  • 3.2.0
Source:
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);

other.value();
// => [9, 16]

wrapped.value();
// => [1, 4]

(static) plant

Creates a clone of the chain sequence planting `value` as the wrapped value.
Since:
  • 3.2.0
Source:
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);

other.value();
// => [9, 16]

wrapped.value();
// => [1, 4]

(static) pull

Removes all given values from `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.without`, this method mutates `array`. Use `_.remove` to remove elements from an array by predicate.
Since:
  • 2.0.0
Source:
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pull(array, 'a', 'c');
console.log(array);
// => ['b', 'b']

(static) pull

Removes all given values from `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.without`, this method mutates `array`. Use `_.remove` to remove elements from an array by predicate.
Since:
  • 2.0.0
Source:
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pull(array, 'a', 'c');
console.log(array);
// => ['b', 'b']

(static) pullAt

Removes elements from `array` corresponding to `indexes` and returns an array of removed elements. **Note:** Unlike `_.at`, this method mutates `array`.
Since:
  • 3.0.0
Source:
Example
var array = ['a', 'b', 'c', 'd'];
var pulled = _.pullAt(array, [1, 3]);

console.log(array);
// => ['a', 'c']

console.log(pulled);
// => ['b', 'd']

(static) pullAt

Removes elements from `array` corresponding to `indexes` and returns an array of removed elements. **Note:** Unlike `_.at`, this method mutates `array`.
Since:
  • 3.0.0
Source:
Example
var array = ['a', 'b', 'c', 'd'];
var pulled = _.pullAt(array, [1, 3]);

console.log(array);
// => ['a', 'c']

console.log(pulled);
// => ['b', 'd']

(static) range

Creates an array of numbers (positive and/or negative) progressing from `start` up to, but not including, `end`. A step of `-1` is used if a negative `start` is specified without an `end` or `step`. If `end` is not specified, it's set to `start` with `start` then set to `0`. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Since:
  • 0.1.0
Source:
See:
  • _.inRange, _.rangeRight
Example
_.range(4);
// => [0, 1, 2, 3]

_.range(-4);
// => [0, -1, -2, -3]

_.range(1, 5);
// => [1, 2, 3, 4]

_.range(0, 20, 5);
// => [0, 5, 10, 15]

_.range(0, -4, -1);
// => [0, -1, -2, -3]

_.range(1, 4, 0);
// => [1, 1, 1]

_.range(0);
// => []

(static) range

Creates an array of numbers (positive and/or negative) progressing from `start` up to, but not including, `end`. A step of `-1` is used if a negative `start` is specified without an `end` or `step`. If `end` is not specified, it's set to `start` with `start` then set to `0`. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Since:
  • 0.1.0
Source:
See:
  • _.inRange, _.rangeRight
Example
_.range(4);
// => [0, 1, 2, 3]

_.range(-4);
// => [0, -1, -2, -3]

_.range(1, 5);
// => [1, 2, 3, 4]

_.range(0, 20, 5);
// => [0, 5, 10, 15]

_.range(0, -4, -1);
// => [0, -1, -2, -3]

_.range(1, 4, 0);
// => [1, 1, 1]

_.range(0);
// => []

(static) rangeRight

This method is like `_.range` except that it populates values in descending order.
Since:
  • 4.0.0
Source:
See:
  • _.inRange, _.range
Example
_.rangeRight(4);
// => [3, 2, 1, 0]

_.rangeRight(-4);
// => [-3, -2, -1, 0]

_.rangeRight(1, 5);
// => [4, 3, 2, 1]

_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]

_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]

_.rangeRight(1, 4, 0);
// => [1, 1, 1]

_.rangeRight(0);
// => []

(static) rangeRight

This method is like `_.range` except that it populates values in descending order.
Since:
  • 4.0.0
Source:
See:
  • _.inRange, _.range
Example
_.rangeRight(4);
// => [3, 2, 1, 0]

_.rangeRight(-4);
// => [-3, -2, -1, 0]

_.rangeRight(1, 5);
// => [4, 3, 2, 1]

_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]

_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]

_.rangeRight(1, 4, 0);
// => [1, 1, 1]

_.rangeRight(0);
// => []

(static) rearg

Creates a function that invokes `func` with arguments arranged according to the specified `indexes` where the argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on.
Since:
  • 3.0.0
Source:
Example
var rearged = _.rearg(function(a, b, c) {
  return [a, b, c];
}, [2, 0, 1]);

rearged('b', 'c', 'a')
// => ['a', 'b', 'c']

(static) rearg

Creates a function that invokes `func` with arguments arranged according to the specified `indexes` where the argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on.
Since:
  • 3.0.0
Source:
Example
var rearged = _.rearg(function(a, b, c) {
  return [a, b, c];
}, [2, 0, 1]);

rearged('b', 'c', 'a')
// => ['a', 'b', 'c']

(static) reverse

This method is the wrapper version of `_.reverse`. **Note:** This method mutates the wrapped array.
Since:
  • 0.1.0
Source:
Example
var array = [1, 2, 3];

_(array).reverse().value()
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) reverse

This method is the wrapper version of `_.reverse`. **Note:** This method mutates the wrapped array.
Since:
  • 0.1.0
Source:
Example
var array = [1, 2, 3];

_(array).reverse().value()
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) round

Computes `number` rounded to `precision`.
Since:
  • 3.10.0
Source:
Example
_.round(4.006);
// => 4

_.round(4.006, 2);
// => 4.01

_.round(4060, -2);
// => 4100

(static) round

Computes `number` rounded to `precision`.
Since:
  • 3.10.0
Source:
Example
_.round(4.006);
// => 4

_.round(4.006, 2);
// => 4.01

_.round(4060, -2);
// => 4100

(static) snakeCase

Converts `string` to [snake case](https://en.wikipedia.org/wiki/Snake_case).
Since:
  • 3.0.0
Source:
Example
_.snakeCase('Foo Bar');
// => 'foo_bar'

_.snakeCase('fooBar');
// => 'foo_bar'

_.snakeCase('--FOO-BAR--');
// => 'foo_bar'

(static) snakeCase

Converts `string` to [snake case](https://en.wikipedia.org/wiki/Snake_case).
Since:
  • 3.0.0
Source:
Example
_.snakeCase('Foo Bar');
// => 'foo_bar'

_.snakeCase('fooBar');
// => 'foo_bar'

_.snakeCase('--FOO-BAR--');
// => 'foo_bar'

(static) sortBy

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) sortBy

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) startCase

Converts `string` to [start case](https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage).
Since:
  • 3.1.0
Source:
Example
_.startCase('--foo-bar--');
// => 'Foo Bar'

_.startCase('fooBar');
// => 'Foo Bar'

_.startCase('__FOO_BAR__');
// => 'FOO BAR'

(static) startCase

Converts `string` to [start case](https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage).
Since:
  • 3.1.0
Source:
Example
_.startCase('--foo-bar--');
// => 'Foo Bar'

_.startCase('fooBar');
// => 'Foo Bar'

_.startCase('__FOO_BAR__');
// => 'FOO BAR'

(static) subtract

Subtract two numbers.
Since:
  • 4.0.0
Source:
Example
_.subtract(6, 4);
// => 2

(static) subtract

Subtract two numbers.
Since:
  • 4.0.0
Source:
Example
_.subtract(6, 4);
// => 2

(static) templateSettings :Object

By default, the template delimiters used by lodash are like those in embedded Ruby (ERB) as well as ES2015 template strings. Change the following template settings to use alternative delimiters.
Type:
  • Object
Source:

(static) toInteger

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Since:
  • 4.0.0
Source:
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toNumber

Converts `value` to a number.
Since:
  • 4.0.0
Source:
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) union

Creates an array of unique values, in order, from all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons.
Since:
  • 0.1.0
Source:
Example
_.union([2], [1, 2]);
// => [2, 1]

(static) union

Creates an array of unique values, in order, from all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons.
Since:
  • 0.1.0
Source:
Example
_.union([2], [1, 2]);
// => [2, 1]

(static) unionBy

This method is like `_.union` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which uniqueness is computed. Result values are chosen from the first array in which the value occurs. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) unionBy

This method is like `_.union` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which uniqueness is computed. Result values are chosen from the first array in which the value occurs. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) unionWith

This method is like `_.union` except that it accepts `comparator` which is invoked to compare elements of `arrays`. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.unionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) unionWith

This method is like `_.union` except that it accepts `comparator` which is invoked to compare elements of `arrays`. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.unionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) upperCase

Converts `string`, as space separated words, to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperCase('--foo-bar');
// => 'FOO BAR'

_.upperCase('fooBar');
// => 'FOO BAR'

_.upperCase('__foo_bar__');
// => 'FOO BAR'

(static) upperCase

Converts `string`, as space separated words, to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperCase('--foo-bar');
// => 'FOO BAR'

_.upperCase('fooBar');
// => 'FOO BAR'

_.upperCase('__foo_bar__');
// => 'FOO BAR'

(static) upperFirst

Converts the first character of `string` to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

(static) upperFirst

Converts the first character of `string` to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

(static) without

Creates an array excluding all given values using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.pull`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2);
// => [3]

(static) without

Creates an array excluding all given values using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.pull`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2);
// => [3]

(static) xor

Creates an array of unique values that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference) of the given arrays. The order of result values is determined by the order they occur in the arrays.
Since:
  • 2.4.0
Source:
See:
  • _.difference, _.without
Example
_.xor([2, 1], [2, 3]);
// => [1, 3]

(static) xor

Creates an array of unique values that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference) of the given arrays. The order of result values is determined by the order they occur in the arrays.
Since:
  • 2.4.0
Source:
See:
  • _.difference, _.without
Example
_.xor([2, 1], [2, 3]);
// => [1, 3]

(static) xorBy

This method is like `_.xor` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which by which they're compared. The order of result values is determined by the order they occur in the arrays. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2, 3.4]

// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) xorBy

This method is like `_.xor` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which by which they're compared. The order of result values is determined by the order they occur in the arrays. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2, 3.4]

// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) xorWith

This method is like `_.xor` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order of result values is determined by the order they occur in the arrays. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.xorWith(objects, others, _.isEqual);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) xorWith

This method is like `_.xor` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order of result values is determined by the order they occur in the arrays. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.xorWith(objects, others, _.isEqual);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
Since:
  • 0.1.0
Source:
Example
_.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

(static) zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
Since:
  • 0.1.0
Source:
Example
_.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

(static) zipWith

This method is like `_.zip` except that it accepts `iteratee` to specify how grouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Since:
  • 3.8.0
Source:
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// => [111, 222]

(static) zipWith

This method is like `_.zip` except that it accepts `iteratee` to specify how grouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Since:
  • 3.8.0
Source:
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// => [111, 222]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

Methods

(static) after(n, func) → {function}

The opposite of `_.before`; this method creates a function that invokes `func` once it's called `n` or more times.
Parameters:
Name Type Description
n number The number of calls before `func` is invoked.
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
  console.log('done saving!');
});

_.forEach(saves, function(type) {
  asyncSave({ 'type': type, 'complete': done });
});
// => Logs 'done saving!' after the two async saves have completed.

(static) after(n, func) → {function}

The opposite of `_.before`; this method creates a function that invokes `func` once it's called `n` or more times.
Parameters:
Name Type Description
n number The number of calls before `func` is invoked.
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
  console.log('done saving!');
});

_.forEach(saves, function(type) {
  asyncSave({ 'type': type, 'complete': done });
});
// => Logs 'done saving!' after the two async saves have completed.

(static) ary(func, nopt) → {function}

Creates a function that invokes `func`, with up to `n` arguments, ignoring any additional arguments.
Parameters:
Name Type Attributes Default Description
func function The function to cap arguments for.
n number <optional>
func.length The arity cap.
Since:
  • 3.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// => [6, 8, 10]

(static) ary(func, nopt) → {function}

Creates a function that invokes `func`, with up to `n` arguments, ignoring any additional arguments.
Parameters:
Name Type Attributes Default Description
func function The function to cap arguments for.
n number <optional>
func.length The arity cap.
Since:
  • 3.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// => [6, 8, 10]

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) capitalize(stringopt) → {string}

Converts the first character of `string` to upper case and the remaining to lower case.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to capitalize.
Since:
  • 3.0.0
Source:
Returns:
Returns the capitalized string.
Type
string
Example
_.capitalize('FRED');
// => 'Fred'

(static) capitalize(stringopt) → {string}

Converts the first character of `string` to upper case and the remaining to lower case.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to capitalize.
Since:
  • 3.0.0
Source:
Returns:
Returns the capitalized string.
Type
string
Example
_.capitalize('FRED');
// => 'Fred'

(static) castArray(value) → {Array}

Casts `value` as an array if it's not one.
Parameters:
Name Type Description
value * The value to inspect.
Since:
  • 4.4.0
Source:
Returns:
Returns the cast array.
Type
Array
Example
_.castArray(1);
// => [1]

_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]

_.castArray('abc');
// => ['abc']

_.castArray(null);
// => [null]

_.castArray(undefined);
// => [undefined]

_.castArray();
// => []

var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

(static) castArray(value) → {Array}

Casts `value` as an array if it's not one.
Parameters:
Name Type Description
value * The value to inspect.
Since:
  • 4.4.0
Source:
Returns:
Returns the cast array.
Type
Array
Example
_.castArray(1);
// => [1]

_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]

_.castArray('abc');
// => ['abc']

_.castArray(null);
// => [null]

_.castArray(undefined);
// => [undefined]

_.castArray();
// => []

var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chunk(array, sizeopt) → {Array}

Creates an array of elements split into groups the length of `size`. If `array` can't be split evenly, the final chunk will be the remaining elements.
Parameters:
Name Type Attributes Default Description
array Array The array to process.
size number <optional>
1 The length of each chunk
Since:
  • 3.0.0
Source:
Returns:
Returns the new array of chunks.
Type
Array
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]

(static) chunk(array, sizeopt) → {Array}

Creates an array of elements split into groups the length of `size`. If `array` can't be split evenly, the final chunk will be the remaining elements.
Parameters:
Name Type Attributes Default Description
array Array The array to process.
size number <optional>
1 The length of each chunk
Since:
  • 3.0.0
Source:
Returns:
Returns the new array of chunks.
Type
Array
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]

(static) clamp(number, loweropt, upper) → {number}

Clamps `number` within the inclusive `lower` and `upper` bounds.
Parameters:
Name Type Attributes Description
number number The number to clamp.
lower number <optional>
The lower bound.
upper number The upper bound.
Since:
  • 4.0.0
Source:
Returns:
Returns the clamped number.
Type
number
Example
_.clamp(-10, -5, 5);
// => -5

_.clamp(10, -5, 5);
// => 5

(static) clamp(number, loweropt, upper) → {number}

Clamps `number` within the inclusive `lower` and `upper` bounds.
Parameters:
Name Type Attributes Description
number number The number to clamp.
lower number <optional>
The lower bound.
upper number The upper bound.
Since:
  • 4.0.0
Source:
Returns:
Returns the clamped number.
Type
number
Example
_.clamp(-10, -5, 5);
// => -5

_.clamp(10, -5, 5);
// => 5

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) cloneDeep(value) → {*}

This method is like `_.clone` except that it recursively clones `value`.
Parameters:
Name Type Description
value * The value to recursively clone.
Since:
  • 1.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false

(static) cloneDeep(value) → {*}

This method is like `_.clone` except that it recursively clones `value`.
Parameters:
Name Type Description
value * The value to recursively clone.
Since:
  • 1.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false

(static) cloneDeepWith(value, customizeropt) → {*}

This method is like `_.cloneWith` except that it recursively clones `value`.
Parameters:
Name Type Attributes Description
value * The value to recursively clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(true);
  }
}

var el = _.cloneDeepWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20

(static) cloneDeepWith(value, customizeropt) → {*}

This method is like `_.cloneWith` except that it recursively clones `value`.
Parameters:
Name Type Attributes Description
value * The value to recursively clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(true);
  }
}

var el = _.cloneDeepWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20

(static) cloneWith(value, customizeropt) → {*}

This method is like `_.clone` except that it accepts `customizer` which is invoked to produce the cloned value. If `customizer` returns `undefined`, cloning is handled by the method instead. The `customizer` is invoked with up to four arguments; (value [, index|key, object, stack]).
Parameters:
Name Type Attributes Description
value * The value to clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(false);
  }
}

var el = _.cloneWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0

(static) cloneWith(value, customizeropt) → {*}

This method is like `_.clone` except that it accepts `customizer` which is invoked to produce the cloned value. If `customizer` returns `undefined`, cloning is handled by the method instead. The `customizer` is invoked with up to four arguments; (value [, index|key, object, stack]).
Parameters:
Name Type Attributes Description
value * The value to clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(false);
  }
}

var el = _.cloneWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) cond(pairs) → {function}

Creates a function that iterates over `pairs` and invokes the corresponding function of the first predicate to return truthy. The predicate-function pairs are invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
pairs Array The predicate-function pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new composite function.
Type
function
Example
var func = _.cond([
  [_.matches({ 'a': 1 }),           _.constant('matches A')],
  [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
  [_.stubTrue,                      _.constant('no match')]
]);

func({ 'a': 1, 'b': 2 });
// => 'matches A'

func({ 'a': 0, 'b': 1 });
// => 'matches B'

func({ 'a': '1', 'b': '2' });
// => 'no match'

(static) cond(pairs) → {function}

Creates a function that iterates over `pairs` and invokes the corresponding function of the first predicate to return truthy. The predicate-function pairs are invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
pairs Array The predicate-function pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new composite function.
Type
function
Example
var func = _.cond([
  [_.matches({ 'a': 1 }),           _.constant('matches A')],
  [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
  [_.stubTrue,                      _.constant('no match')]
]);

func({ 'a': 1, 'b': 2 });
// => 'matches A'

func({ 'a': 0, 'b': 1 });
// => 'matches B'

func({ 'a': '1', 'b': '2' });
// => 'no match'

(static) conforms(source) → {function}

Creates a function that invokes the predicate properties of `source` with the corresponding property values of a given object, returning `true` if all predicates return truthy, else `false`. **Note:** The created function is equivalent to `_.conformsTo` with `source` partially applied.
Parameters:
Name Type Description
source Object The object of property predicates to conform to.
Since:
  • 4.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 2, 'b': 1 },
  { 'a': 1, 'b': 2 }
];

_.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } }));
// => [{ 'a': 1, 'b': 2 }]

(static) conforms(source) → {function}

Creates a function that invokes the predicate properties of `source` with the corresponding property values of a given object, returning `true` if all predicates return truthy, else `false`. **Note:** The created function is equivalent to `_.conformsTo` with `source` partially applied.
Parameters:
Name Type Description
source Object The object of property predicates to conform to.
Since:
  • 4.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 2, 'b': 1 },
  { 'a': 1, 'b': 2 }
];

_.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } }));
// => [{ 'a': 1, 'b': 2 }]

(static) conformsTo(object, source) → {boolean}

Checks if `object` conforms to `source` by invoking the predicate properties of `source` with the corresponding property values of `object`. **Note:** This method is equivalent to `_.conforms` when `source` is partially applied.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property predicates to conform to.
Since:
  • 4.14.0
Source:
Returns:
Returns `true` if `object` conforms, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.conformsTo(object, { 'b': function(n) { return n > 1; } });
// => true

_.conformsTo(object, { 'b': function(n) { return n > 2; } });
// => false

(static) conformsTo(object, source) → {boolean}

Checks if `object` conforms to `source` by invoking the predicate properties of `source` with the corresponding property values of `object`. **Note:** This method is equivalent to `_.conforms` when `source` is partially applied.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property predicates to conform to.
Since:
  • 4.14.0
Source:
Returns:
Returns `true` if `object` conforms, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.conformsTo(object, { 'b': function(n) { return n > 1; } });
// => true

_.conformsTo(object, { 'b': function(n) { return n > 2; } });
// => false

(static) constant(value) → {function}

Creates a function that returns `value`.
Parameters:
Name Type Description
value * The value to return from the new function.
Since:
  • 2.4.0
Source:
Returns:
Returns the new constant function.
Type
function
Example
var objects = _.times(2, _.constant({ 'a': 1 }));

console.log(objects);
// => [{ 'a': 1 }, { 'a': 1 }]

console.log(objects[0] === objects[1]);
// => true

(static) constant(value) → {function}

Creates a function that returns `value`.
Parameters:
Name Type Description
value * The value to return from the new function.
Since:
  • 2.4.0
Source:
Returns:
Returns the new constant function.
Type
function
Example
var objects = _.times(2, _.constant({ 'a': 1 }));

console.log(objects);
// => [{ 'a': 1 }, { 'a': 1 }]

console.log(objects[0] === objects[1]);
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) curry(func, arityopt) → {function}

Creates a function that accepts arguments of `func` and either invokes `func` returning its result, if at least `arity` number of arguments have been provided, or returns a function that accepts the remaining `func` arguments, and so on. The arity of `func` may be specified if `func.length` is not sufficient. The `_.curry.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 2.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curry(abc);

curried(1)(2)(3);
// => [1, 2, 3]

curried(1, 2)(3);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]

(static) curry(func, arityopt) → {function}

Creates a function that accepts arguments of `func` and either invokes `func` returning its result, if at least `arity` number of arguments have been provided, or returns a function that accepts the remaining `func` arguments, and so on. The arity of `func` may be specified if `func.length` is not sufficient. The `_.curry.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 2.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curry(abc);

curried(1)(2)(3);
// => [1, 2, 3]

curried(1, 2)(3);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]

(static) curryRight(func, arityopt) → {function}

This method is like `_.curry` except that arguments are applied to `func` in the manner of `_.partialRight` instead of `_.partial`. The `_.curryRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 3.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curryRight(abc);

curried(3)(2)(1);
// => [1, 2, 3]

curried(2, 3)(1);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]

(static) curryRight(func, arityopt) → {function}

This method is like `_.curry` except that arguments are applied to `func` in the manner of `_.partialRight` instead of `_.partial`. The `_.curryRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 3.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curryRight(abc);

curried(3)(2)(1);
// => [1, 2, 3]

curried(2, 3)(1);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]

(static) debounce(func, waitopt, optionsopt) → {function}

Creates a debounced function that delays invoking `func` until after `wait` milliseconds have elapsed since the last time the debounced function was invoked. The debounced function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the debounced function. Subsequent calls to the debounced function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the debounced function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.debounce` and `_.throttle`.
Parameters:
Name Type Attributes Default Description
func function The function to debounce.
wait number <optional>
0 The number of milliseconds to delay.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait number <optional>
The maximum time `func` is allowed to be delayed before it's invoked.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new debounced function.
Type
function
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));

// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));

// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);

// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);

(static) debounce(func, waitopt, optionsopt) → {function}

Creates a debounced function that delays invoking `func` until after `wait` milliseconds have elapsed since the last time the debounced function was invoked. The debounced function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the debounced function. Subsequent calls to the debounced function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the debounced function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.debounce` and `_.throttle`.
Parameters:
Name Type Attributes Default Description
func function The function to debounce.
wait number <optional>
0 The number of milliseconds to delay.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait number <optional>
The maximum time `func` is allowed to be delayed before it's invoked.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new debounced function.
Type
function
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));

// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));

// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);

// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);

(static) deburr(stringopt) → {string}

Deburrs `string` by converting [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table) and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A) letters to basic Latin letters and removing [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to deburr.
Since:
  • 3.0.0
Source:
Returns:
Returns the deburred string.
Type
string
Example
_.deburr('déjà vu');
// => 'deja vu'

(static) deburr(stringopt) → {string}

Deburrs `string` by converting [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table) and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A) letters to basic Latin letters and removing [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to deburr.
Since:
  • 3.0.0
Source:
Returns:
Returns the deburred string.
Type
string
Example
_.deburr('déjà vu');
// => 'deja vu'

(static) defaultTo(value, defaultValue) → {*}

Checks `value` to determine whether a default value should be returned in its place. The `defaultValue` is returned if `value` is `NaN`, `null`, or `undefined`.
Parameters:
Name Type Description
value * The value to check.
defaultValue * The default value.
Since:
  • 4.14.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
_.defaultTo(1, 10);
// => 1

_.defaultTo(undefined, 10);
// => 10

(static) defaultTo(value, defaultValue) → {*}

Checks `value` to determine whether a default value should be returned in its place. The `defaultValue` is returned if `value` is `NaN`, `null`, or `undefined`.
Parameters:
Name Type Description
value * The value to check.
defaultValue * The default value.
Since:
  • 4.14.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
_.defaultTo(1, 10);
// => 1

_.defaultTo(undefined, 10);
// => 10

(static) drop(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 0.5.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

_.drop([1, 2, 3], 5);
// => []

_.drop([1, 2, 3], 0);
// => [1, 2, 3]

(static) drop(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 0.5.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

_.drop([1, 2, 3], 5);
// => []

_.drop([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

_.dropRight([1, 2, 3], 5);
// => []

_.dropRight([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

_.dropRight([1, 2, 3], 5);
// => []

_.dropRight([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the end. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.dropRightWhile(users, function(o) { return !o.active; });
// => objects for ['barney']

// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['barney', 'fred']

// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// => objects for ['barney']

// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the end. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.dropRightWhile(users, function(o) { return !o.active; });
// => objects for ['barney']

// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['barney', 'fred']

// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// => objects for ['barney']

// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the beginning. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.dropWhile(users, function(o) { return !o.active; });
// => objects for ['pebbles']

// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['fred', 'pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// => objects for ['pebbles']

// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the beginning. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.dropWhile(users, function(o) { return !o.active; });
// => objects for ['pebbles']

// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['fred', 'pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// => objects for ['pebbles']

// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) eachRight(collection, iterateeopt) → {Array|Object}

This method is like `_.forEach` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
  • _.forEach
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEachRight([1, 2], function(value) {
  console.log(value);
});
// => Logs `2` then `1`.

(static) eachRight(collection, iterateeopt) → {Array|Object}

This method is like `_.forEach` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
  • _.forEach
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEachRight([1, 2], function(value) {
  console.log(value);
});
// => Logs `2` then `1`.

(static) endsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` ends with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
string.length The position to search up to.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` ends with `target`, else `false`.
Type
boolean
Example
_.endsWith('abc', 'c');
// => true

_.endsWith('abc', 'b');
// => false

_.endsWith('abc', 'b', 2);
// => true

(static) endsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` ends with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
string.length The position to search up to.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` ends with `target`, else `false`.
Type
boolean
Example
_.endsWith('abc', 'c');
// => true

_.endsWith('abc', 'b');
// => false

_.endsWith('abc', 'b', 2);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escapeRegExp(stringopt) → {string}

Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+", "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 3.0.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'

(static) escapeRegExp(stringopt) → {string}

Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+", "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 3.0.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) fill(array, value, startopt, endopt) → {Array}

Fills elements of `array` with `value` from `start` up to, but not including, `end`. **Note:** This method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to fill.
value * The value to fill `array` with.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.2.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.fill(array, 'a');
console.log(array);
// => ['a', 'a', 'a']

_.fill(Array(3), 2);
// => [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3);
// => [4, '*', '*', 10]

(static) fill(array, value, startopt, endopt) → {Array}

Fills elements of `array` with `value` from `start` up to, but not including, `end`. **Note:** This method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to fill.
value * The value to fill `array` with.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.2.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.fill(array, 'a');
console.log(array);
// => ['a', 'a', 'a']

_.fill(Array(3), 2);
// => [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3);
// => [4, '*', '*', 10]

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findKey(object, predicateopt) → {string|undefined}

This method is like `_.find` except that it returns the key of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 1.1.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

(static) findKey(object, predicateopt) → {string|undefined}

This method is like `_.find` except that it returns the key of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 1.1.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

(static) findLastIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.findIndex` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 2.0.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// => 2

// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// => 0

// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// => 2

// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// => 0

(static) findLastIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.findIndex` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 2.0.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// => 2

// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// => 0

// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// => 2

// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// => 0

(static) findLastKey(object, predicateopt) → {string|undefined}

This method is like `_.findKey` except that it iterates over elements of a collection in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'

// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'

// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'

(static) findLastKey(object, predicateopt) → {string|undefined}

This method is like `_.findKey` except that it iterates over elements of a collection in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'

// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'

// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) flatMap(collection, iterateeopt) → {Array}

Creates a flattened array of values by running each element in `collection` thru `iteratee` and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [n, n];
}

_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMap(collection, iterateeopt) → {Array}

Creates a flattened array of values by running each element in `collection` thru `iteratee` and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [n, n];
}

_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDeep(collection, iterateeopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDeep([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDeep(collection, iterateeopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDeep([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDepth(collection, iterateeopt, depthopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results up to `depth` times.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDepth([1, 2], duplicate, 2);
// => [[1, 1], [2, 2]]

(static) flatMapDepth(collection, iterateeopt, depthopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results up to `depth` times.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDepth([1, 2], duplicate, 2);
// => [[1, 1], [2, 2]]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDepth(array, depthopt) → {Array}

Recursively flatten `array` up to `depth` times.
Parameters:
Name Type Attributes Default Description
array Array The array to flatten.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.4.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
var array = [1, [2, [3, [4]], 5]];

_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]

_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

(static) flattenDepth(array, depthopt) → {Array}

Recursively flatten `array` up to `depth` times.
Parameters:
Name Type Attributes Default Description
array Array The array to flatten.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.4.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
var array = [1, [2, [3, [4]], 5]];

_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]

_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

(static) flip(func) → {function}

Creates a function that invokes `func` with arguments reversed.
Parameters:
Name Type Description
func function The function to flip arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flipped function.
Type
function
Example
var flipped = _.flip(function() {
  return _.toArray(arguments);
});

flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']

(static) flip(func) → {function}

Creates a function that invokes `func` with arguments reversed.
Parameters:
Name Type Description
func function The function to flip arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flipped function.
Type
function
Example
var flipped = _.flip(function() {
  return _.toArray(arguments);
});

flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']

(static) forIn(object, iterateeopt) → {Object}

Iterates over own and inherited enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forIn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).

(static) forIn(object, iterateeopt) → {Object}

Iterates over own and inherited enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forIn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).

(static) forInRight(object, iterateeopt) → {Object}

This method is like `_.forIn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forInRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.

(static) forInRight(object, iterateeopt) → {Object}

This method is like `_.forIn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forInRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.

(static) forOwn(object, iterateeopt) → {Object}

Iterates over own enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) forOwn(object, iterateeopt) → {Object}

Iterates over own enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) forOwnRight(object, iterateeopt) → {Object}

This method is like `_.forOwn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwnRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.

(static) forOwnRight(object, iterateeopt) → {Object}

This method is like `_.forOwn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwnRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.

(static) fromPairs(pairs) → {Object}

The inverse of `_.toPairs`; this method returns an object composed from key-value `pairs`.
Parameters:
Name Type Description
pairs Array The key-value pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

(static) fromPairs(pairs) → {Object}

The inverse of `_.toPairs`; this method returns an object composed from key-value `pairs`.
Parameters:
Name Type Description
pairs Array The key-value pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

(static) functions(object) → {Array}

Creates an array of function property names from own enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functions(new Foo);
// => ['a', 'b']

(static) functions(object) → {Array}

Creates an array of function property names from own enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functions(new Foo);
// => ['a', 'b']

(static) functionsIn(object) → {Array}

Creates an array of function property names from own and inherited enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functionsIn(new Foo);
// => ['a', 'b', 'c']

(static) functionsIn(object) → {Array}

Creates an array of function property names from own and inherited enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functionsIn(new Foo);
// => ['a', 'b', 'c']

(static) get(object, path, defaultValueopt) → {*}

Gets the value at `path` of `object`. If the resolved value is `undefined`, the `defaultValue` is returned in its place.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to get.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 3.7.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.get(object, 'a[0].b.c');
// => 3

_.get(object, ['a', '0', 'b', 'c']);
// => 3

_.get(object, 'a.b.c', 'default');
// => 'default'

(static) get(object, path, defaultValueopt) → {*}

Gets the value at `path` of `object`. If the resolved value is `undefined`, the `defaultValue` is returned in its place.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to get.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 3.7.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.get(object, 'a[0].b.c');
// => 3

_.get(object, ['a', '0', 'b', 'c']);
// => 3

_.get(object, 'a.b.c', 'default');
// => 'default'

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) hasIn(object, path) → {boolean}

Checks if `path` is a direct or inherited property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) });

_.hasIn(object, 'a');
// => true

_.hasIn(object, 'a.b');
// => true

_.hasIn(object, ['a', 'b']);
// => true

_.hasIn(object, 'b');
// => false

(static) hasIn(object, path) → {boolean}

Checks if `path` is a direct or inherited property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) });

_.hasIn(object, 'a');
// => true

_.hasIn(object, 'a.b');
// => true

_.hasIn(object, ['a', 'b']);
// => true

_.hasIn(object, 'b');
// => false

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) inRange(number, startopt, end) → {boolean}

Checks if `n` is between `start` and up to, but not including, `end`. If `end` is not specified, it's set to `start` with `start` then set to `0`. If `start` is greater than `end` the params are swapped to support negative ranges.
Parameters:
Name Type Attributes Default Description
number number The number to check.
start number <optional>
0 The start of the range.
end number The end of the range.
Since:
  • 3.3.0
Source:
See:
  • _.range, _.rangeRight
Returns:
Returns `true` if `number` is in the range, else `false`.
Type
boolean
Example
_.inRange(3, 2, 4);
// => true

_.inRange(4, 8);
// => true

_.inRange(4, 2);
// => false

_.inRange(2, 2);
// => false

_.inRange(1.2, 2);
// => true

_.inRange(5.2, 4);
// => false

_.inRange(-3, -2, -6);
// => true

(static) inRange(number, startopt, end) → {boolean}

Checks if `n` is between `start` and up to, but not including, `end`. If `end` is not specified, it's set to `start` with `start` then set to `0`. If `start` is greater than `end` the params are swapped to support negative ranges.
Parameters:
Name Type Attributes Default Description
number number The number to check.
start number <optional>
0 The start of the range.
end number The end of the range.
Since:
  • 3.3.0
Source:
See:
  • _.range, _.rangeRight
Returns:
Returns `true` if `number` is in the range, else `false`.
Type
boolean
Example
_.inRange(3, 2, 4);
// => true

_.inRange(4, 8);
// => true

_.inRange(4, 2);
// => false

_.inRange(2, 2);
// => false

_.inRange(1.2, 2);
// => true

_.inRange(5.2, 4);
// => false

_.inRange(-3, -2, -6);
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) initial(array) → {Array}

Gets all but the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.initial([1, 2, 3]);
// => [1, 2]

(static) initial(array) → {Array}

Gets all but the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.initial([1, 2, 3]);
// => [1, 2]

(static) isArguments(value) → {boolean}

Checks if `value` is likely an `arguments` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an `arguments` object, else `false`.
Type
boolean
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isElement(value) → {boolean}

Checks if `value` is likely a DOM element.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a DOM element, else `false`.
Type
boolean
Example
_.isElement(document.body);
// => true

_.isElement('<body>');
// => false

(static) isElement(value) → {boolean}

Checks if `value` is likely a DOM element.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a DOM element, else `false`.
Type
boolean
Example
_.isElement(document.body);
// => true

_.isElement('<body>');
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqualWith(value, other, customizeropt) → {boolean}

This method is like `_.isEqual` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with up to six arguments: (objValue, othValue [, index|key, object, other, stack]).
Parameters:
Name Type Attributes Description
value * The value to compare.
other * The other value to compare.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, othValue) {
  if (isGreeting(objValue) && isGreeting(othValue)) {
    return true;
  }
}

var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];

_.isEqualWith(array, other, customizer);
// => true

(static) isEqualWith(value, other, customizeropt) → {boolean}

This method is like `_.isEqual` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with up to six arguments: (objValue, othValue [, index|key, object, other, stack]).
Parameters:
Name Type Attributes Description
value * The value to compare.
other * The other value to compare.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, othValue) {
  if (isGreeting(objValue) && isGreeting(othValue)) {
    return true;
  }
}

var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];

_.isEqualWith(array, other, customizer);
// => true

(static) isError(value) → {boolean}

Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, or `URIError` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is an error object, else `false`.
Type
boolean
Example
_.isError(new Error);
// => true

_.isError(Error);
// => false

(static) isError(value) → {boolean}

Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, or `URIError` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is an error object, else `false`.
Type
boolean
Example
_.isError(new Error);
// => true

_.isError(Error);
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isMatch(object, source) → {boolean}

Performs a partial deep comparison between `object` and `source` to determine if `object` contains equivalent property values. **Note:** This method is equivalent to `_.matches` when `source` is partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.isMatch(object, { 'b': 2 });
// => true

_.isMatch(object, { 'b': 1 });
// => false

(static) isMatch(object, source) → {boolean}

Performs a partial deep comparison between `object` and `source` to determine if `object` contains equivalent property values. **Note:** This method is equivalent to `_.matches` when `source` is partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.isMatch(object, { 'b': 2 });
// => true

_.isMatch(object, { 'b': 1 });
// => false

(static) isMatchWith(object, source, customizeropt) → {boolean}

This method is like `_.isMatch` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, index|key, object, source).
Parameters:
Name Type Attributes Description
object Object The object to inspect.
source Object The object of property values to match.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, srcValue) {
  if (isGreeting(objValue) && isGreeting(srcValue)) {
    return true;
  }
}

var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };

_.isMatchWith(object, source, customizer);
// => true

(static) isMatchWith(object, source, customizeropt) → {boolean}

This method is like `_.isMatch` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, index|key, object, source).
Parameters:
Name Type Attributes Description
object Object The object to inspect.
source Object The object of property values to match.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, srcValue) {
  if (isGreeting(objValue) && isGreeting(srcValue)) {
    return true;
  }
}

var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };

_.isMatchWith(object, source, customizer);
// => true

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNative(value) → {boolean}

Checks if `value` is a pristine native function. **Note:** This method can't reliably detect native functions in the presence of the core-js package because core-js circumvents this kind of detection. Despite multiple requests, the core-js maintainer has made it clear: any attempt to fix the detection will be obstructed. As a result, we're left with little choice but to throw an error. Unfortunately, this also affects packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill), which rely on core-js.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is a native function, else `false`.
Type
boolean
Example
_.isNative(Array.prototype.push);
// => true

_.isNative(_);
// => false

(static) isNative(value) → {boolean}

Checks if `value` is a pristine native function. **Note:** This method can't reliably detect native functions in the presence of the core-js package because core-js circumvents this kind of detection. Despite multiple requests, the core-js maintainer has made it clear: any attempt to fix the detection will be obstructed. As a result, we're left with little choice but to throw an error. Unfortunately, this also affects packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill), which rely on core-js.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is a native function, else `false`.
Type
boolean
Example
_.isNative(Array.prototype.push);
// => true

_.isNative(_);
// => false

(static) isNil(value) → {boolean}

Checks if `value` is `null` or `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is nullish, else `false`.
Type
boolean
Example
_.isNil(null);
// => true

_.isNil(void 0);
// => true

_.isNil(NaN);
// => false

(static) isNil(value) → {boolean}

Checks if `value` is `null` or `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is nullish, else `false`.
Type
boolean
Example
_.isNil(null);
// => true

_.isNil(void 0);
// => true

_.isNil(NaN);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isSafeInteger(value) → {boolean}

Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754 double precision number which isn't the result of a rounded unsafe integer. **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a safe integer, else `false`.
Type
boolean
Example
_.isSafeInteger(3);
// => true

_.isSafeInteger(Number.MIN_VALUE);
// => false

_.isSafeInteger(Infinity);
// => false

_.isSafeInteger('3');
// => false

(static) isSafeInteger(value) → {boolean}

Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754 double precision number which isn't the result of a rounded unsafe integer. **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a safe integer, else `false`.
Type
boolean
Example
_.isSafeInteger(3);
// => true

_.isSafeInteger(Number.MIN_VALUE);
// => false

_.isSafeInteger(Infinity);
// => false

_.isSafeInteger('3');
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isWeakMap(value) → {boolean}

Checks if `value` is classified as a `WeakMap` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak map, else `false`.
Type
boolean
Example
_.isWeakMap(new WeakMap);
// => true

_.isWeakMap(new Map);
// => false

(static) isWeakMap(value) → {boolean}

Checks if `value` is classified as a `WeakMap` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak map, else `false`.
Type
boolean
Example
_.isWeakMap(new WeakMap);
// => true

_.isWeakMap(new Map);
// => false

(static) isWeakSet(value) → {boolean}

Checks if `value` is classified as a `WeakSet` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak set, else `false`.
Type
boolean
Example
_.isWeakSet(new WeakSet);
// => true

_.isWeakSet(new Set);
// => false

(static) isWeakSet(value) → {boolean}

Checks if `value` is classified as a `WeakSet` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak set, else `false`.
Type
boolean
Example
_.isWeakSet(new WeakSet);
// => true

_.isWeakSet(new Set);
// => false

(static) iteratee(funcopt) → {function}

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Parameters:
Name Type Attributes Default Description
func * <optional>
_.identity The value to convert to a callback.
Since:
  • 4.0.0
Source:
Returns:
Returns the callback.
Type
function
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) iteratee(funcopt) → {function}

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Parameters:
Name Type Attributes Default Description
func * <optional>
_.identity The value to convert to a callback.
Since:
  • 4.0.0
Source:
Returns:
Returns the callback.
Type
function
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) join(array, separatoropt) → {string}

Converts all elements in `array` into a string separated by `separator`.
Parameters:
Name Type Attributes Default Description
array Array The array to convert.
separator string <optional>
',' The element separator.
Since:
  • 4.0.0
Source:
Returns:
Returns the joined string.
Type
string
Example
_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'

(static) join(array, separatoropt) → {string}

Converts all elements in `array` into a string separated by `separator`.
Parameters:
Name Type Attributes Default Description
array Array The array to convert.
separator string <optional>
',' The element separator.
Since:
  • 4.0.0
Source:
Returns:
Returns the joined string.
Type
string
Example
_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keysIn(object) → {Array}

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) keysIn(object) → {Array}

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) lastIndexOf(array, value, fromIndexopt) → {number}

This method is like `_.indexOf` except that it iterates over elements of `array` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// => 3

// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// => 1

(static) lastIndexOf(array, value, fromIndexopt) → {number}

This method is like `_.indexOf` except that it iterates over elements of `array` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// => 3

// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// => 1

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) mapKeys(object, iterateeopt) → {Object}

The opposite of `_.mapValues`; this method creates an object with the same values as `object` and keys generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.8.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
  return key + value;
});
// => { 'a1': 1, 'b2': 2 }

(static) mapKeys(object, iterateeopt) → {Object}

The opposite of `_.mapValues`; this method creates an object with the same values as `object` and keys generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.8.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
  return key + value;
});
// => { 'a1': 1, 'b2': 2 }

(static) mapValues(object, iterateeopt) → {Object}

Creates an object with the same keys as `object` and values generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.4.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

(static) mapValues(object, iterateeopt) → {Object}

Creates an object with the same keys as `object` and values generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.4.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matchesProperty(path, srcValue) → {function}

Creates a function that performs a partial deep comparison between the value at `path` of a given object to `srcValue`, returning `true` if the object value is equivalent, else `false`. **Note:** Partial comparisons will match empty array and empty object `srcValue` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
path Array | string The path of the property to get.
srcValue * The value to match.
Since:
  • 3.2.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.find(objects, _.matchesProperty('a', 4));
// => { 'a': 4, 'b': 5, 'c': 6 }

// Checking for several possible values
_.filter(objects, _.overSome([_.matchesProperty('a', 1), _.matchesProperty('a', 4)]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matchesProperty(path, srcValue) → {function}

Creates a function that performs a partial deep comparison between the value at `path` of a given object to `srcValue`, returning `true` if the object value is equivalent, else `false`. **Note:** Partial comparisons will match empty array and empty object `srcValue` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
path Array | string The path of the property to get.
srcValue * The value to match.
Since:
  • 3.2.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.find(objects, _.matchesProperty('a', 4));
// => { 'a': 4, 'b': 5, 'c': 6 }

// Checking for several possible values
_.filter(objects, _.overSome([_.matchesProperty('a', 1), _.matchesProperty('a', 4)]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) maxBy(array, iterateeopt) → {*}

This method is like `_.max` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.maxBy(objects, function(o) { return o.n; });
// => { 'n': 2 }

// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// => { 'n': 2 }

(static) maxBy(array, iterateeopt) → {*}

This method is like `_.max` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.maxBy(objects, function(o) { return o.n; });
// => { 'n': 2 }

// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// => { 'n': 2 }

(static) mean(array) → {number}

Computes the mean of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 4.0.0
Source:
Returns:
Returns the mean.
Type
number
Example
_.mean([4, 2, 8, 6]);
// => 5

(static) mean(array) → {number}

Computes the mean of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 4.0.0
Source:
Returns:
Returns the mean.
Type
number
Example
_.mean([4, 2, 8, 6]);
// => 5

(static) meanBy(array, iterateeopt) → {number}

This method is like `_.mean` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be averaged. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.7.0
Source:
Returns:
Returns the mean.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.meanBy(objects, function(o) { return o.n; });
// => 5

// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// => 5

(static) meanBy(array, iterateeopt) → {number}

This method is like `_.mean` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be averaged. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.7.0
Source:
Returns:
Returns the mean.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.meanBy(objects, function(o) { return o.n; });
// => 5

// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// => 5

(static) memoize(func, resolveropt) → {function}

Creates a function that memoizes the result of `func`. If `resolver` is provided, it determines the cache key for storing the result based on the arguments provided to the memoized function. By default, the first argument provided to the memoized function is used as the map cache key. The `func` is invoked with the `this` binding of the memoized function. **Note:** The cache is exposed as the `cache` property on the memoized function. Its creation may be customized by replacing the `_.memoize.Cache` constructor with one whose instances implement the [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) method interface of `clear`, `delete`, `get`, `has`, and `set`.
Parameters:
Name Type Attributes Description
func function The function to have its output memoized.
resolver function <optional>
The function to resolve the cache key.
Since:
  • 0.1.0
Source:
Returns:
Returns the new memoized function.
Type
function
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };

var values = _.memoize(_.values);
values(object);
// => [1, 2]

values(other);
// => [3, 4]

object.a = 2;
values(object);
// => [1, 2]

// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']

// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;

(static) memoize(func, resolveropt) → {function}

Creates a function that memoizes the result of `func`. If `resolver` is provided, it determines the cache key for storing the result based on the arguments provided to the memoized function. By default, the first argument provided to the memoized function is used as the map cache key. The `func` is invoked with the `this` binding of the memoized function. **Note:** The cache is exposed as the `cache` property on the memoized function. Its creation may be customized by replacing the `_.memoize.Cache` constructor with one whose instances implement the [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) method interface of `clear`, `delete`, `get`, `has`, and `set`.
Parameters:
Name Type Attributes Description
func function The function to have its output memoized.
resolver function <optional>
The function to resolve the cache key.
Since:
  • 0.1.0
Source:
Returns:
Returns the new memoized function.
Type
function
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };

var values = _.memoize(_.values);
values(object);
// => [1, 2]

values(other);
// => [3, 4]

object.a = 2;
values(object);
// => [1, 2]

// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']

// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) minBy(array, iterateeopt) → {*}

This method is like `_.min` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }

// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

(static) minBy(array, iterateeopt) → {*}

This method is like `_.min` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }

// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) noConflict() → {function}

Reverts the `_` variable to its previous value and returns a reference to the `lodash` function.
Since:
  • 0.1.0
Source:
Returns:
Returns the `lodash` function.
Type
function
Example
var lodash = _.noConflict();

(static) noConflict() → {function}

Reverts the `_` variable to its previous value and returns a reference to the `lodash` function.
Since:
  • 0.1.0
Source:
Returns:
Returns the `lodash` function.
Type
function
Example
var lodash = _.noConflict();

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) now() → {number}

Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
Since:
  • 2.4.0
Source:
Returns:
Returns the timestamp.
Type
number
Example
_.defer(function(stamp) {
  console.log(_.now() - stamp);
}, _.now());
// => Logs the number of milliseconds it took for the deferred invocation.

(static) nth(array, nopt) → {*}

Gets the element at index `n` of `array`. If `n` is negative, the nth element from the end is returned.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
0 The index of the element to return.
Since:
  • 4.11.0
Source:
Returns:
Returns the nth element of `array`.
Type
*
Example
var array = ['a', 'b', 'c', 'd'];

_.nth(array, 1);
// => 'b'

_.nth(array, -2);
// => 'c';

(static) nth(array, nopt) → {*}

Gets the element at index `n` of `array`. If `n` is negative, the nth element from the end is returned.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
0 The index of the element to return.
Since:
  • 4.11.0
Source:
Returns:
Returns the nth element of `array`.
Type
*
Example
var array = ['a', 'b', 'c', 'd'];

_.nth(array, 1);
// => 'b'

_.nth(array, -2);
// => 'c';

(static) nthArg(nopt) → {function}

Creates a function that gets the argument at index `n`. If `n` is negative, the nth argument from the end is returned.
Parameters:
Name Type Attributes Default Description
n number <optional>
0 The index of the argument to return.
Since:
  • 4.0.0
Source:
Returns:
Returns the new pass-thru function.
Type
function
Example
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// => 'b'

var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// => 'c'

(static) nthArg(nopt) → {function}

Creates a function that gets the argument at index `n`. If `n` is negative, the nth argument from the end is returned.
Parameters:
Name Type Attributes Default Description
n number <optional>
0 The index of the argument to return.
Since:
  • 4.0.0
Source:
Returns:
Returns the new pass-thru function.
Type
function
Example
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// => 'b'

var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// => 'c'

(static) omitBy(object, predicateopt) → {Object}

The opposite of `_.pickBy`; this method creates an object composed of the own and inherited enumerable string keyed properties of `object` that `predicate` doesn't return truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omitBy(object, _.isNumber);
// => { 'b': '2' }

(static) omitBy(object, predicateopt) → {Object}

The opposite of `_.pickBy`; this method creates an object composed of the own and inherited enumerable string keyed properties of `object` that `predicate` doesn't return truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omitBy(object, _.isNumber);
// => { 'b': '2' }

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) orderBy(collection, iterateesopt, ordersopt) → {Array}

This method is like `_.sortBy` except that it allows specifying the sort orders of the iteratees to sort by. If `orders` is unspecified, all values are sorted in ascending order. Otherwise, specify an order of "desc" for descending or "asc" for ascending sort order of corresponding values.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees Array:.<Array:> | Array:.<function()> | Array:.<Object:> | Array:.<string:> <optional>
[_.identity] The iteratees to sort by.
orders Array:.<string:> <optional>
The sort orders of `iteratees`.
Since:
  • 4.0.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 34 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 36 }
];

// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

(static) orderBy(collection, iterateesopt, ordersopt) → {Array}

This method is like `_.sortBy` except that it allows specifying the sort orders of the iteratees to sort by. If `orders` is unspecified, all values are sorted in ascending order. Otherwise, specify an order of "desc" for descending or "asc" for ascending sort order of corresponding values.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees Array:.<Array:> | Array:.<function()> | Array:.<Object:> | Array:.<string:> <optional>
[_.identity] The iteratees to sort by.
orders Array:.<string:> <optional>
The sort orders of `iteratees`.
Since:
  • 4.0.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 34 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 36 }
];

// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

(static) pad(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left and right sides if it's shorter than `length`. Padding characters are truncated if they can't be evenly divided by `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 3.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.pad('abc', 8);
// => '  abc   '

_.pad('abc', 8, '_-');
// => '_-abc_-_'

_.pad('abc', 3);
// => 'abc'

(static) pad(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left and right sides if it's shorter than `length`. Padding characters are truncated if they can't be evenly divided by `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 3.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.pad('abc', 8);
// => '  abc   '

_.pad('abc', 8, '_-');
// => '_-abc_-_'

_.pad('abc', 3);
// => 'abc'

(static) padEnd(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the right side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padEnd('abc', 6);
// => 'abc   '

_.padEnd('abc', 6, '_-');
// => 'abc_-_'

_.padEnd('abc', 3);
// => 'abc'

(static) padEnd(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the right side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padEnd('abc', 6);
// => 'abc   '

_.padEnd('abc', 6, '_-');
// => 'abc_-_'

_.padEnd('abc', 3);
// => 'abc'

(static) padStart(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padStart('abc', 6);
// => '   abc'

_.padStart('abc', 6, '_-');
// => '_-_abc'

_.padStart('abc', 3);
// => 'abc'

(static) padStart(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padStart('abc', 6);
// => '   abc'

_.padStart('abc', 6, '_-');
// => '_-_abc'

_.padStart('abc', 3);
// => 'abc'

(static) parseInt(string, radixopt) → {number}

Converts `string` to an integer of the specified radix. If `radix` is `undefined` or `0`, a `radix` of `10` is used unless `value` is a hexadecimal, in which case a `radix` of `16` is used. **Note:** This method aligns with the [ES5 implementation](https://es5.github.io/#x15.1.2.2) of `parseInt`.
Parameters:
Name Type Attributes Default Description
string string The string to convert.
radix number <optional>
10 The radix to interpret `value` by.
Since:
  • 1.1.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.parseInt('08');
// => 8

_.map(['6', '08', '10'], _.parseInt);
// => [6, 8, 10]

(static) parseInt(string, radixopt) → {number}

Converts `string` to an integer of the specified radix. If `radix` is `undefined` or `0`, a `radix` of `10` is used unless `value` is a hexadecimal, in which case a `radix` of `16` is used. **Note:** This method aligns with the [ES5 implementation](https://es5.github.io/#x15.1.2.2) of `parseInt`.
Parameters:
Name Type Attributes Default Description
string string The string to convert.
radix number <optional>
10 The radix to interpret `value` by.
Since:
  • 1.1.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.parseInt('08');
// => 8

_.map(['6', '08', '10'], _.parseInt);
// => [6, 8, 10]

(static) pickBy(object, predicateopt) → {Object}

Creates an object composed of the `object` properties `predicate` returns truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

(static) pickBy(object, predicateopt) → {Object}

Creates an object composed of the `object` properties `predicate` returns truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

(static) property(path) → {function}

Creates a function that returns the value at `path` of a given object.
Parameters:
Name Type Description
path Array | string The path of the property to get.
Since:
  • 2.4.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];

_.map(objects, _.property('a.b'));
// => [2, 1]

_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// => [1, 2]

(static) property(path) → {function}

Creates a function that returns the value at `path` of a given object.
Parameters:
Name Type Description
path Array | string The path of the property to get.
Since:
  • 2.4.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];

_.map(objects, _.property('a.b'));
// => [2, 1]

_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// => [1, 2]

(static) propertyOf(object) → {function}

The opposite of `_.property`; this method creates a function that returns the value at a given path of `object`.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var array = [0, 1, 2],
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// => [2, 0]

(static) propertyOf(object) → {function}

The opposite of `_.property`; this method creates a function that returns the value at a given path of `object`.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var array = [0, 1, 2],
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// => [2, 0]

(static) pullAll(array, values) → {Array}

This method is like `_.pull` except that it accepts an array of values to remove. **Note:** Unlike `_.difference`, this method mutates `array`.
Parameters:
Name Type Description
array Array The array to modify.
values Array The values to remove.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pullAll(array, ['a', 'c']);
console.log(array);
// => ['b', 'b']

(static) pullAll(array, values) → {Array}

This method is like `_.pull` except that it accepts an array of values to remove. **Note:** Unlike `_.difference`, this method mutates `array`.
Parameters:
Name Type Description
array Array The array to modify.
values Array The values to remove.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pullAll(array, ['a', 'c']);
console.log(array);
// => ['b', 'b']

(static) pullAllBy(array, values, iterateeopt) → {Array}

This method is like `_.pullAll` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.differenceBy`, this method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
values Array The values to remove.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];

_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// => [{ 'x': 2 }]

(static) pullAllBy(array, values, iterateeopt) → {Array}

This method is like `_.pullAll` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.differenceBy`, this method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
values Array The values to remove.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];

_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// => [{ 'x': 2 }]

(static) pullAllWith(array, values, comparatoropt) → {Array}

This method is like `_.pullAll` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.differenceWith`, this method mutates `array`.
Parameters:
Name Type Attributes Description
array Array The array to modify.
values Array The values to remove.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.6.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];

_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]

(static) pullAllWith(array, values, comparatoropt) → {Array}

This method is like `_.pullAll` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.differenceWith`, this method mutates `array`.
Parameters:
Name Type Attributes Description
array Array The array to modify.
values Array The values to remove.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.6.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];

_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]

(static) random(loweropt, upperopt, floatingopt) → {number}

Produces a random number between the inclusive `lower` and `upper` bounds. If only one argument is provided a number between `0` and the given number is returned. If `floating` is `true`, or either `lower` or `upper` are floats, a floating-point number is returned instead of an integer. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Parameters:
Name Type Attributes Default Description
lower number <optional>
0 The lower bound.
upper number <optional>
1 The upper bound.
floating boolean <optional>
Specify returning a floating-point number.
Since:
  • 0.7.0
Source:
Returns:
Returns the random number.
Type
number
Example
_.random(0, 5);
// => an integer between 0 and 5

_.random(5);
// => also an integer between 0 and 5

_.random(5, true);
// => a floating-point number between 0 and 5

_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2

(static) random(loweropt, upperopt, floatingopt) → {number}

Produces a random number between the inclusive `lower` and `upper` bounds. If only one argument is provided a number between `0` and the given number is returned. If `floating` is `true`, or either `lower` or `upper` are floats, a floating-point number is returned instead of an integer. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Parameters:
Name Type Attributes Default Description
lower number <optional>
0 The lower bound.
upper number <optional>
1 The upper bound.
floating boolean <optional>
Specify returning a floating-point number.
Since:
  • 0.7.0
Source:
Returns:
Returns the random number.
Type
number
Example
_.random(0, 5);
// => an integer between 0 and 5

_.random(5);
// => also an integer between 0 and 5

_.random(5, true);
// => a floating-point number between 0 and 5

_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduceRight(collection, iterateeopt, accumulatoropt) → {*}

This method is like `_.reduce` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
var array = [[0, 1], [2, 3], [4, 5]];

_.reduceRight(array, function(flattened, other) {
  return flattened.concat(other);
}, []);
// => [4, 5, 2, 3, 0, 1]

(static) reduceRight(collection, iterateeopt, accumulatoropt) → {*}

This method is like `_.reduce` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
var array = [[0, 1], [2, 3], [4, 5]];

_.reduceRight(array, function(flattened, other) {
  return flattened.concat(other);
}, []);
// => [4, 5, 2, 3, 0, 1]

(static) reject(collection, predicateopt) → {Array}

The opposite of `_.filter`; this method returns the elements of `collection` that `predicate` does **not** return truthy for.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': true }
];

_.reject(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// => objects for ['barney']

(static) reject(collection, predicateopt) → {Array}

The opposite of `_.filter`; this method returns the elements of `collection` that `predicate` does **not** return truthy for.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': true }
];

_.reject(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// => objects for ['barney']

(static) remove(array, predicateopt) → {Array}

Removes all elements from `array` that `predicate` returns truthy for and returns an array of the removed elements. The predicate is invoked with three arguments: (value, index, array). **Note:** Unlike `_.filter`, this method mutates `array`. Use `_.pull` to pull elements from an array by value.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the new array of removed elements.
Type
Array
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

(static) remove(array, predicateopt) → {Array}

Removes all elements from `array` that `predicate` returns truthy for and returns an array of the removed elements. The predicate is invoked with three arguments: (value, index, array). **Note:** Unlike `_.filter`, this method mutates `array`. Use `_.pull` to pull elements from an array by value.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the new array of removed elements.
Type
Array
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

(static) repeat(stringopt, nopt) → {string}

Repeats the given string `n` times.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to repeat.
n number <optional>
1 The number of times to repeat the string.
Since:
  • 3.0.0
Source:
Returns:
Returns the repeated string.
Type
string
Example
_.repeat('*', 3);
// => '***'

_.repeat('abc', 2);
// => 'abcabc'

_.repeat('abc', 0);
// => ''

(static) repeat(stringopt, nopt) → {string}

Repeats the given string `n` times.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to repeat.
n number <optional>
1 The number of times to repeat the string.
Since:
  • 3.0.0
Source:
Returns:
Returns the repeated string.
Type
string
Example
_.repeat('*', 3);
// => '***'

_.repeat('abc', 2);
// => 'abcabc'

_.repeat('abc', 0);
// => ''

(static) replace(stringopt, pattern, replacement) → {string}

Replaces matches for `pattern` in `string` with `replacement`. **Note:** This method is based on [`String#replace`](https://mdn.io/String/replace).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to modify.
pattern RegExp | string The pattern to replace.
replacement function | string The match replacement.
Since:
  • 4.0.0
Source:
Returns:
Returns the modified string.
Type
string
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// => 'Hi Barney'

(static) replace(stringopt, pattern, replacement) → {string}

Replaces matches for `pattern` in `string` with `replacement`. **Note:** This method is based on [`String#replace`](https://mdn.io/String/replace).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to modify.
pattern RegExp | string The pattern to replace.
replacement function | string The match replacement.
Since:
  • 4.0.0
Source:
Returns:
Returns the modified string.
Type
string
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// => 'Hi Barney'

(static) rest(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the created function and arguments from `start` and beyond provided as an array. **Note:** This method is based on the [rest parameter](https://mdn.io/rest_parameters).
Parameters:
Name Type Attributes Default Description
func function The function to apply a rest parameter to.
start number <optional>
func.length-1 The start position of the rest parameter.
Since:
  • 4.0.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.rest(function(what, names) {
  return what + ' ' + _.initial(names).join(', ') +
    (_.size(names) > 1 ? ', & ' : '') + _.last(names);
});

say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'

(static) rest(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the created function and arguments from `start` and beyond provided as an array. **Note:** This method is based on the [rest parameter](https://mdn.io/rest_parameters).
Parameters:
Name Type Attributes Default Description
func function The function to apply a rest parameter to.
start number <optional>
func.length-1 The start position of the rest parameter.
Since:
  • 4.0.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.rest(function(what, names) {
  return what + ' ' + _.initial(names).join(', ') +
    (_.size(names) > 1 ? ', & ' : '') + _.last(names);
});

say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) reverse(array) → {Array}

Reverses `array` so that the first element becomes the last, the second element becomes the second to last, and so on. **Note:** This method mutates `array` and is based on [`Array#reverse`](https://mdn.io/Array/reverse).
Parameters:
Name Type Description
array Array The array to modify.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) reverse(array) → {Array}

Reverses `array` so that the first element becomes the last, the second element becomes the second to last, and so on. **Note:** This method mutates `array` and is based on [`Array#reverse`](https://mdn.io/Array/reverse).
Parameters:
Name Type Description
array Array The array to modify.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) runInContext(contextopt) → {function}

Create a new pristine `lodash` function using the `context` object.
Parameters:
Name Type Attributes Default Description
context Object <optional>
root The context object.
Since:
  • 1.1.0
Source:
Returns:
Returns a new `lodash` function.
Type
function
Example
_.mixin({ 'foo': _.constant('foo') });

var lodash = _.runInContext();
lodash.mixin({ 'bar': lodash.constant('bar') });

_.isFunction(_.foo);
// => true
_.isFunction(_.bar);
// => false

lodash.isFunction(lodash.foo);
// => false
lodash.isFunction(lodash.bar);
// => true

// Create a suped-up `defer` in Node.js.
var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;

(static) sample(collection) → {*}

Gets a random element from `collection`.
Parameters:
Name Type Description
collection Array | Object The collection to sample.
Since:
  • 2.0.0
Source:
Returns:
Returns the random element.
Type
*
Example
_.sample([1, 2, 3, 4]);
// => 2

(static) sample(collection) → {*}

Gets a random element from `collection`.
Parameters:
Name Type Description
collection Array | Object The collection to sample.
Since:
  • 2.0.0
Source:
Returns:
Returns the random element.
Type
*
Example
_.sample([1, 2, 3, 4]);
// => 2

(static) sampleSize(collection, nopt) → {Array}

Gets `n` random elements at unique keys from `collection` up to the size of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to sample.
n number <optional>
1 The number of elements to sample.
Since:
  • 4.0.0
Source:
Returns:
Returns the random elements.
Type
Array
Example
_.sampleSize([1, 2, 3], 2);
// => [3, 1]

_.sampleSize([1, 2, 3], 4);
// => [2, 3, 1]

(static) sampleSize(collection, nopt) → {Array}

Gets `n` random elements at unique keys from `collection` up to the size of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to sample.
n number <optional>
1 The number of elements to sample.
Since:
  • 4.0.0
Source:
Returns:
Returns the random elements.
Type
Array
Example
_.sampleSize([1, 2, 3], 2);
// => [3, 1]

_.sampleSize([1, 2, 3], 4);
// => [2, 3, 1]

(static) set(object, path, value) → {Object}

Sets the value at `path` of `object`. If a portion of `path` doesn't exist, it's created. Arrays are created for missing index properties while objects are created for all other missing properties. Use `_.setWith` to customize `path` creation. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
Since:
  • 3.7.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// => 4

_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// => 5

(static) set(object, path, value) → {Object}

Sets the value at `path` of `object`. If a portion of `path` doesn't exist, it's created. Arrays are created for missing index properties while objects are created for all other missing properties. Use `_.setWith` to customize `path` creation. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
Since:
  • 3.7.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// => 4

_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// => 5

(static) setWith(object, path, value, customizeropt) → {Object}

This method is like `_.set` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.0.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.setWith(object, '[0][1]', 'a', Object);
// => { '0': { '1': 'a' } }

(static) setWith(object, path, value, customizeropt) → {Object}

This method is like `_.set` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.0.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.setWith(object, '[0][1]', 'a', Object);
// => { '0': { '1': 'a' } }

(static) shuffle(collection) → {Array}

Creates an array of shuffled values, using a version of the [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
Parameters:
Name Type Description
collection Array | Object The collection to shuffle.
Since:
  • 0.1.0
Source:
Returns:
Returns the new shuffled array.
Type
Array
Example
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]

(static) shuffle(collection) → {Array}

Creates an array of shuffled values, using a version of the [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
Parameters:
Name Type Description
collection Array | Object The collection to shuffle.
Since:
  • 0.1.0
Source:
Returns:
Returns the new shuffled array.
Type
Array
Example
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) sortBy(collection, …iterateesopt) → {Array}

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees function | Array:.<function()> <optional>
<repeatable>
[_.identity] The iteratees to sort by.
Since:
  • 0.1.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) sortedIndex(array, value) → {number}

Uses a binary search to determine the lowest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 0.1.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedIndex([30, 50], 40);
// => 1

(static) sortedIndex(array, value) → {number}

Uses a binary search to determine the lowest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 0.1.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedIndex([30, 50], 40);
// => 1

(static) sortedIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 0

// The `_.property` iteratee shorthand.
_.sortedIndexBy(objects, { 'x': 4 }, 'x');
// => 0

(static) sortedIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 0

// The `_.property` iteratee shorthand.
_.sortedIndexBy(objects, { 'x': 4 }, 'x');
// => 0

(static) sortedIndexOf(array, value) → {number}

This method is like `_.indexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5);
// => 1

(static) sortedIndexOf(array, value) → {number}

This method is like `_.indexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5);
// => 1

(static) sortedLastIndex(array, value) → {number}

This method is like `_.sortedIndex` except that it returns the highest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 3.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5);
// => 4

(static) sortedLastIndex(array, value) → {number}

This method is like `_.sortedIndex` except that it returns the highest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 3.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5);
// => 4

(static) sortedLastIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedLastIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 1

// The `_.property` iteratee shorthand.
_.sortedLastIndexBy(objects, { 'x': 4 }, 'x');
// => 1

(static) sortedLastIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedLastIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 1

// The `_.property` iteratee shorthand.
_.sortedLastIndexBy(objects, { 'x': 4 }, 'x');
// => 1

(static) sortedLastIndexOf(array, value) → {number}

This method is like `_.lastIndexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5);
// => 3

(static) sortedLastIndexOf(array, value) → {number}

This method is like `_.lastIndexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5);
// => 3

(static) sortedUniq(array) → {Array}

This method is like `_.uniq` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniq([1, 1, 2]);
// => [1, 2]

(static) sortedUniq(array) → {Array}

This method is like `_.uniq` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniq([1, 1, 2]);
// => [1, 2]

(static) sortedUniqBy(array, iterateeopt) → {Array}

This method is like `_.uniqBy` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Attributes Description
array Array The array to inspect.
iteratee function <optional>
The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// => [1.1, 2.3]

(static) sortedUniqBy(array, iterateeopt) → {Array}

This method is like `_.uniqBy` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Attributes Description
array Array The array to inspect.
iteratee function <optional>
The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// => [1.1, 2.3]

(static) split(stringopt, separator, limitopt) → {Array}

Splits `string` by `separator`. **Note:** This method is based on [`String#split`](https://mdn.io/String/split).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to split.
separator RegExp | string The separator pattern to split by.
limit number <optional>
The length to truncate results to.
Since:
  • 4.0.0
Source:
Returns:
Returns the string segments.
Type
Array
Example
_.split('a-b-c', '-', 2);
// => ['a', 'b']

(static) split(stringopt, separator, limitopt) → {Array}

Splits `string` by `separator`. **Note:** This method is based on [`String#split`](https://mdn.io/String/split).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to split.
separator RegExp | string The separator pattern to split by.
limit number <optional>
The length to truncate results to.
Since:
  • 4.0.0
Source:
Returns:
Returns the string segments.
Type
Array
Example
_.split('a-b-c', '-', 2);
// => ['a', 'b']

(static) spread(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the create function and an array of arguments much like [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply). **Note:** This method is based on the [spread operator](https://mdn.io/spread_operator).
Parameters:
Name Type Attributes Default Description
func function The function to spread arguments over.
start number <optional>
0 The start position of the spread.
Since:
  • 3.2.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.spread(function(who, what) {
  return who + ' says ' + what;
});

say(['fred', 'hello']);
// => 'fred says hello'

var numbers = Promise.all([
  Promise.resolve(40),
  Promise.resolve(36)
]);

numbers.then(_.spread(function(x, y) {
  return x + y;
}));
// => a Promise of 76

(static) spread(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the create function and an array of arguments much like [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply). **Note:** This method is based on the [spread operator](https://mdn.io/spread_operator).
Parameters:
Name Type Attributes Default Description
func function The function to spread arguments over.
start number <optional>
0 The start position of the spread.
Since:
  • 3.2.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.spread(function(who, what) {
  return who + ' says ' + what;
});

say(['fred', 'hello']);
// => 'fred says hello'

var numbers = Promise.all([
  Promise.resolve(40),
  Promise.resolve(36)
]);

numbers.then(_.spread(function(x, y) {
  return x + y;
}));
// => a Promise of 76

(static) startsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` starts with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
0 The position to search from.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` starts with `target`, else `false`.
Type
boolean
Example
_.startsWith('abc', 'a');
// => true

_.startsWith('abc', 'b');
// => false

_.startsWith('abc', 'b', 1);
// => true

(static) startsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` starts with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
0 The position to search from.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` starts with `target`, else `false`.
Type
boolean
Example
_.startsWith('abc', 'a');
// => true

_.startsWith('abc', 'b');
// => false

_.startsWith('abc', 'b', 1);
// => true

(static) stubArray() → {Array}

This method returns a new empty array.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty array.
Type
Array
Example
var arrays = _.times(2, _.stubArray);

console.log(arrays);
// => [[], []]

console.log(arrays[0] === arrays[1]);
// => false

(static) stubArray() → {Array}

This method returns a new empty array.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty array.
Type
Array
Example
var arrays = _.times(2, _.stubArray);

console.log(arrays);
// => [[], []]

console.log(arrays[0] === arrays[1]);
// => false

(static) stubFalse() → {boolean}

This method returns `false`.
Since:
  • 4.13.0
Source:
Returns:
Returns `false`.
Type
boolean
Example
_.times(2, _.stubFalse);
// => [false, false]

(static) stubFalse() → {boolean}

This method returns `false`.
Since:
  • 4.13.0
Source:
Returns:
Returns `false`.
Type
boolean
Example
_.times(2, _.stubFalse);
// => [false, false]

(static) stubObject() → {Object}

This method returns a new empty object.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty object.
Type
Object
Example
var objects = _.times(2, _.stubObject);

console.log(objects);
// => [{}, {}]

console.log(objects[0] === objects[1]);
// => false

(static) stubObject() → {Object}

This method returns a new empty object.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty object.
Type
Object
Example
var objects = _.times(2, _.stubObject);

console.log(objects);
// => [{}, {}]

console.log(objects[0] === objects[1]);
// => false

(static) stubString() → {string}

This method returns an empty string.
Since:
  • 4.13.0
Source:
Returns:
Returns the empty string.
Type
string
Example
_.times(2, _.stubString);
// => ['', '']

(static) stubString() → {string}

This method returns an empty string.
Since:
  • 4.13.0
Source:
Returns:
Returns the empty string.
Type
string
Example
_.times(2, _.stubString);
// => ['', '']

(static) stubTrue() → {boolean}

This method returns `true`.
Since:
  • 4.13.0
Source:
Returns:
Returns `true`.
Type
boolean
Example
_.times(2, _.stubTrue);
// => [true, true]

(static) stubTrue() → {boolean}

This method returns `true`.
Since:
  • 4.13.0
Source:
Returns:
Returns `true`.
Type
boolean
Example
_.times(2, _.stubTrue);
// => [true, true]

(static) sum(array) → {number}

Computes the sum of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 3.4.0
Source:
Returns:
Returns the sum.
Type
number
Example
_.sum([4, 2, 8, 6]);
// => 20

(static) sum(array) → {number}

Computes the sum of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 3.4.0
Source:
Returns:
Returns the sum.
Type
number
Example
_.sum([4, 2, 8, 6]);
// => 20

(static) sumBy(array, iterateeopt) → {number}

This method is like `_.sum` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be summed. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the sum.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.sumBy(objects, function(o) { return o.n; });
// => 20

// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20

(static) sumBy(array, iterateeopt) → {number}

This method is like `_.sum` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be summed. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the sum.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.sumBy(objects, function(o) { return o.n; });
// => 20

// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20

(static) tail(array) → {Array}

Gets all but the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 4.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.tail([1, 2, 3]);
// => [2, 3]

(static) tail(array) → {Array}

Gets all but the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 4.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.tail([1, 2, 3]);
// => [2, 3]

(static) take(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.take([1, 2, 3]);
// => [1]

_.take([1, 2, 3], 2);
// => [1, 2]

_.take([1, 2, 3], 5);
// => [1, 2, 3]

_.take([1, 2, 3], 0);
// => []

(static) take(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.take([1, 2, 3]);
// => [1]

_.take([1, 2, 3], 2);
// => [1, 2]

_.take([1, 2, 3], 5);
// => [1, 2, 3]

_.take([1, 2, 3], 0);
// => []

(static) takeRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

_.takeRight([1, 2, 3], 0);
// => []

(static) takeRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

_.takeRight([1, 2, 3], 0);
// => []

(static) takeRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the end. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.takeRightWhile(users, function(o) { return !o.active; });
// => objects for ['fred', 'pebbles']

// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// => objects for ['fred', 'pebbles']

// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// => []

(static) takeRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the end. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.takeRightWhile(users, function(o) { return !o.active; });
// => objects for ['fred', 'pebbles']

// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// => objects for ['fred', 'pebbles']

// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// => []

(static) takeWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the beginning. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.takeWhile(users, function(o) { return !o.active; });
// => objects for ['barney', 'fred']

// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// => objects for ['barney', 'fred']

// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// => []

(static) takeWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the beginning. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.takeWhile(users, function(o) { return !o.active; });
// => objects for ['barney', 'fred']

// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// => objects for ['barney', 'fred']

// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// => []

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) template(stringopt, optionsopt) → {function}

Creates a compiled template function that can interpolate data properties in "interpolate" delimiters, HTML-escape interpolated data properties in "escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data properties may be accessed as free variables in the template. If a setting object is given, it takes precedence over `_.templateSettings` values. **Note:** In the development build `_.template` utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging. For more information on precompiling templates see [lodash's custom builds documentation](https://lodash.com/custom-builds). For more information on Chrome extension sandboxes see [Chrome's extensions documentation](https://developer.chrome.com/extensions/sandboxingEval).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The template string.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
escape RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL string <optional>
'lodash.templateSources[n]' The sourceURL of the compiled template.
variable string <optional>
'obj' The data object variable name.
Since:
  • 0.1.0
Source:
Returns:
Returns the compiled template function.
Type
function
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'

// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b>&lt;script&gt;</b>'

// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'

// Use the ES template literal delimiter as an "interpolate" delimiter.
// Disable support by replacing the "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'

// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'

// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.

// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// => function(data) {
//   var __t, __p = '';
//   __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
//   return __p;
// }

// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'

// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\
  var JST = {\
    "main": ' + _.template(mainText).source + '\
  };\
');

(static) template(stringopt, optionsopt) → {function}

Creates a compiled template function that can interpolate data properties in "interpolate" delimiters, HTML-escape interpolated data properties in "escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data properties may be accessed as free variables in the template. If a setting object is given, it takes precedence over `_.templateSettings` values. **Note:** In the development build `_.template` utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging. For more information on precompiling templates see [lodash's custom builds documentation](https://lodash.com/custom-builds). For more information on Chrome extension sandboxes see [Chrome's extensions documentation](https://developer.chrome.com/extensions/sandboxingEval).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The template string.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
escape RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL string <optional>
'templateSources[n]' The sourceURL of the compiled template.
variable string <optional>
'obj' The data object variable name.
Since:
  • 0.1.0
Source:
Returns:
Returns the compiled template function.
Type
function
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'

// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b>&lt;script&gt;</b>'

// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'

// Use the ES template literal delimiter as an "interpolate" delimiter.
// Disable support by replacing the "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'

// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'

// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.

// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// => function(data) {
//   var __t, __p = '';
//   __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
//   return __p;
// }

// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'

// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\
  var JST = {\
    "main": ' + _.template(mainText).source + '\
  };\
');

(static) throttle(func, waitopt, optionsopt) → {function}

Creates a throttled function that only invokes `func` at most once per every `wait` milliseconds. The throttled function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the throttled function. Subsequent calls to the throttled function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the throttled function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.throttle` and `_.debounce`.
Parameters:
Name Type Attributes Default Description
func function The function to throttle.
wait number <optional>
0 The number of milliseconds to throttle invocations to.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new throttled function.
Type
function
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));

// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);

// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);

(static) throttle(func, waitopt, optionsopt) → {function}

Creates a throttled function that only invokes `func` at most once per every `wait` milliseconds. The throttled function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the throttled function. Subsequent calls to the throttled function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the throttled function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.throttle` and `_.debounce`.
Parameters:
Name Type Attributes Default Description
func function The function to throttle.
wait number <optional>
0 The number of milliseconds to throttle invocations to.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new throttled function.
Type
function
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));

// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);

// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) times(n, iterateeopt) → {Array}

Invokes the iteratee `n` times, returning an array of the results of each invocation. The iteratee is invoked with one argument; (index).
Parameters:
Name Type Attributes Default Description
n number The number of times to invoke `iteratee`.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of results.
Type
Array
Example
_.times(3, String);
// => ['0', '1', '2']

 _.times(4, _.constant(0));
// => [0, 0, 0, 0]

(static) times(n, iterateeopt) → {Array}

Invokes the iteratee `n` times, returning an array of the results of each invocation. The iteratee is invoked with one argument; (index).
Parameters:
Name Type Attributes Default Description
n number The number of times to invoke `iteratee`.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of results.
Type
Array
Example
_.times(3, String);
// => ['0', '1', '2']

 _.times(4, _.constant(0));
// => [0, 0, 0, 0]

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toLength(value) → {number}

Converts `value` to an integer suitable for use as the length of an array-like object. **Note:** This method is based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toLength(3.2);
// => 3

_.toLength(Number.MIN_VALUE);
// => 0

_.toLength(Infinity);
// => 4294967295

_.toLength('3.2');
// => 3

(static) toLength(value) → {number}

Converts `value` to an integer suitable for use as the length of an array-like object. **Note:** This method is based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toLength(3.2);
// => 3

_.toLength(Number.MIN_VALUE);
// => 0

_.toLength(Infinity);
// => 4294967295

_.toLength('3.2');
// => 3

(static) toLower(stringopt) → {string}

Converts `string`, as a whole, to lower case just like [String#toLowerCase](https://mdn.io/toLowerCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the lower cased string.
Type
string
Example
_.toLower('--Foo-Bar--');
// => '--foo-bar--'

_.toLower('fooBar');
// => 'foobar'

_.toLower('__FOO_BAR__');
// => '__foo_bar__'

(static) toLower(stringopt) → {string}

Converts `string`, as a whole, to lower case just like [String#toLowerCase](https://mdn.io/toLowerCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the lower cased string.
Type
string
Example
_.toLower('--Foo-Bar--');
// => '--foo-bar--'

_.toLower('fooBar');
// => 'foobar'

_.toLower('__FOO_BAR__');
// => '__foo_bar__'

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toPath(value) → {Array}

Converts `value` to a property path array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the new property path array.
Type
Array
Example
_.toPath('a.b.c');
// => ['a', 'b', 'c']

_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']

(static) toPath(value) → {Array}

Converts `value` to a property path array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the new property path array.
Type
Array
Example
_.toPath('a.b.c');
// => ['a', 'b', 'c']

_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']

(static) toPlainObject(value) → {Object}

Converts `value` to a plain object flattening inherited enumerable string keyed properties of `value` to own properties of the plain object.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 3.0.0
Source:
Returns:
Returns the converted plain object.
Type
Object
Example
function Foo() {
  this.b = 2;
}

Foo.prototype.c = 3;

_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }

_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }

(static) toPlainObject(value) → {Object}

Converts `value` to a plain object flattening inherited enumerable string keyed properties of `value` to own properties of the plain object.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 3.0.0
Source:
Returns:
Returns the converted plain object.
Type
Object
Example
function Foo() {
  this.b = 2;
}

Foo.prototype.c = 3;

_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }

_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }

(static) toSafeInteger(value) → {number}

Converts `value` to a safe integer. A safe integer can be compared and represented correctly.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toSafeInteger(3.2);
// => 3

_.toSafeInteger(Number.MIN_VALUE);
// => 0

_.toSafeInteger(Infinity);
// => 9007199254740991

_.toSafeInteger('3.2');
// => 3

(static) toSafeInteger(value) → {number}

Converts `value` to a safe integer. A safe integer can be compared and represented correctly.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toSafeInteger(3.2);
// => 3

_.toSafeInteger(Number.MIN_VALUE);
// => 0

_.toSafeInteger(Infinity);
// => 9007199254740991

_.toSafeInteger('3.2');
// => 3

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toUpper(stringopt) → {string}

Converts `string`, as a whole, to upper case just like [String#toUpperCase](https://mdn.io/toUpperCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the upper cased string.
Type
string
Example
_.toUpper('--foo-bar--');
// => '--FOO-BAR--'

_.toUpper('fooBar');
// => 'FOOBAR'

_.toUpper('__foo_bar__');
// => '__FOO_BAR__'

(static) toUpper(stringopt) → {string}

Converts `string`, as a whole, to upper case just like [String#toUpperCase](https://mdn.io/toUpperCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the upper cased string.
Type
string
Example
_.toUpper('--foo-bar--');
// => '--FOO-BAR--'

_.toUpper('fooBar');
// => 'FOOBAR'

_.toUpper('__foo_bar__');
// => '__FOO_BAR__'

(static) transform(object, iterateeopt, accumulatoropt) → {*}

An alternative to `_.reduce`; this method transforms `object` to a new `accumulator` object which is the result of running each of its own enumerable string keyed properties thru `iteratee`, with each invocation potentially mutating the `accumulator` object. If `accumulator` is not provided, a new object with the same `[[Prototype]]` will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The custom accumulator value.
Since:
  • 1.3.0
Source:
Returns:
Returns the accumulated value.
Type
*
Example
_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
}, []);
// => [4, 9]

_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
}, {});
// => { '1': ['a', 'c'], '2': ['b'] }

(static) transform(object, iterateeopt, accumulatoropt) → {*}

An alternative to `_.reduce`; this method transforms `object` to a new `accumulator` object which is the result of running each of its own enumerable string keyed properties thru `iteratee`, with each invocation potentially mutating the `accumulator` object. If `accumulator` is not provided, a new object with the same `[[Prototype]]` will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The custom accumulator value.
Since:
  • 1.3.0
Source:
Returns:
Returns the accumulated value.
Type
*
Example
_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
}, []);
// => [4, 9]

_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
}, {});
// => { '1': ['a', 'c'], '2': ['b'] }

(static) trim(stringopt, charsopt) → {string}

Removes leading and trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 3.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trim('  abc  ');
// => 'abc'

_.trim('-_-abc-_-', '_-');
// => 'abc'

_.map(['  foo  ', '  bar  '], _.trim);
// => ['foo', 'bar']

(static) trim(stringopt, charsopt) → {string}

Removes leading and trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 3.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trim('  abc  ');
// => 'abc'

_.trim('-_-abc-_-', '_-');
// => 'abc'

_.map(['  foo  ', '  bar  '], _.trim);
// => ['foo', 'bar']

(static) trimEnd(stringopt, charsopt) → {string}

Removes trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimEnd('  abc  ');
// => '  abc'

_.trimEnd('-_-abc-_-', '_-');
// => '-_-abc'

(static) trimEnd(stringopt, charsopt) → {string}

Removes trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimEnd('  abc  ');
// => '  abc'

_.trimEnd('-_-abc-_-', '_-');
// => '-_-abc'

(static) trimStart(stringopt, charsopt) → {string}

Removes leading whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimStart('  abc  ');
// => 'abc  '

_.trimStart('-_-abc-_-', '_-');
// => 'abc-_-'

(static) trimStart(stringopt, charsopt) → {string}

Removes leading whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimStart('  abc  ');
// => 'abc  '

_.trimStart('-_-abc-_-', '_-');
// => 'abc-_-'

(static) truncate(stringopt, optionsopt) → {string}

Truncates `string` if it's longer than the given maximum string length. The last characters of the truncated string are replaced with the omission string which defaults to "...".
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to truncate.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
length number <optional>
30 The maximum string length.
omission string <optional>
'...' The string to indicate text is omitted.
separator RegExp | string <optional>
The separator pattern to truncate to.
Since:
  • 4.0.0
Source:
Returns:
Returns the truncated string.
Type
string
Example
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': ' '
});
// => 'hi-diddly-ho there,...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': /,? +/
});
// => 'hi-diddly-ho there...'

_.truncate('hi-diddly-ho there, neighborino', {
  'omission': ' [...]'
});
// => 'hi-diddly-ho there, neig [...]'

(static) truncate(stringopt, optionsopt) → {string}

Truncates `string` if it's longer than the given maximum string length. The last characters of the truncated string are replaced with the omission string which defaults to "...".
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to truncate.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
length number <optional>
30 The maximum string length.
omission string <optional>
'...' The string to indicate text is omitted.
separator RegExp | string <optional>
The separator pattern to truncate to.
Since:
  • 4.0.0
Source:
Returns:
Returns the truncated string.
Type
string
Example
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': ' '
});
// => 'hi-diddly-ho there,...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': /,? +/
});
// => 'hi-diddly-ho there...'

_.truncate('hi-diddly-ho there, neighborino', {
  'omission': ' [...]'
});
// => 'hi-diddly-ho there, neig [...]'

(static) unary(func) → {function}

Creates a function that accepts up to one argument, ignoring any additional arguments.
Parameters:
Name Type Description
func function The function to cap arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// => [6, 8, 10]

(static) unary(func) → {function}

Creates a function that accepts up to one argument, ignoring any additional arguments.
Parameters:
Name Type Description
func function The function to cap arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// => [6, 8, 10]

(static) unescape(stringopt) → {string}

The inverse of `_.escape`; this method converts the HTML entities `&`, `<`, `>`, `"`, and `'` in `string` to their corresponding characters. **Note:** No other HTML entities are unescaped. To unescape additional HTML entities use a third-party library like [_he_](https://mths.be/he).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to unescape.
Since:
  • 0.6.0
Source:
Returns:
Returns the unescaped string.
Type
string
Example
_.unescape('fred, barney, &amp; pebbles');
// => 'fred, barney, & pebbles'

(static) unescape(stringopt) → {string}

The inverse of `_.escape`; this method converts the HTML entities `&`, `<`, `>`, `"`, and `'` in `string` to their corresponding characters. **Note:** No other HTML entities are unescaped. To unescape additional HTML entities use a third-party library like [_he_](https://mths.be/he).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to unescape.
Since:
  • 0.6.0
Source:
Returns:
Returns the unescaped string.
Type
string
Example
_.unescape('fred, barney, &amp; pebbles');
// => 'fred, barney, & pebbles'

(static) uniq(array) → {Array}

Creates a duplicate-free version of an array, using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniq([2, 1, 2]);
// => [2, 1]

(static) uniq(array) → {Array}

Creates a duplicate-free version of an array, using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniq([2, 1, 2]);
// => [2, 1]

(static) uniqBy(array, iterateeopt) → {Array}

This method is like `_.uniq` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which uniqueness is computed. The order of result values is determined by the order they occur in the array. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) uniqBy(array, iterateeopt) → {Array}

This method is like `_.uniq` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which uniqueness is computed. The order of result values is determined by the order they occur in the array. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) uniqWith(array, comparatoropt) → {Array}

This method is like `_.uniq` except that it accepts `comparator` which is invoked to compare elements of `array`. The order of result values is determined by the order they occur in the array.The comparator is invoked with two arguments: (arrVal, othVal).
Parameters:
Name Type Attributes Description
array Array The array to inspect.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

(static) uniqWith(array, comparatoropt) → {Array}

This method is like `_.uniq` except that it accepts `comparator` which is invoked to compare elements of `array`. The order of result values is determined by the order they occur in the array.The comparator is invoked with two arguments: (arrVal, othVal).
Parameters:
Name Type Attributes Description
array Array The array to inspect.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) unset(object, path) → {boolean}

Removes the property at `path` of `object`. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to unset.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the property is deleted, else `false`.
Type
boolean
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

_.unset(object, ['a', '0', 'b', 'c']);
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

(static) unset(object, path) → {boolean}

Removes the property at `path` of `object`. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to unset.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the property is deleted, else `false`.
Type
boolean
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

_.unset(object, ['a', '0', 'b', 'c']);
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

(static) unzip(array) → {Array}

This method is like `_.zip` except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.
Parameters:
Name Type Description
array Array The array of grouped elements to process.
Since:
  • 1.2.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

_.unzip(zipped);
// => [['a', 'b'], [1, 2], [true, false]]

(static) unzip(array) → {Array}

This method is like `_.zip` except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.
Parameters:
Name Type Description
array Array The array of grouped elements to process.
Since:
  • 1.2.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

_.unzip(zipped);
// => [['a', 'b'], [1, 2], [true, false]]

(static) unzipWith(array, iterateeopt) → {Array}

This method is like `_.unzip` except that it accepts `iteratee` to specify how regrouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Parameters:
Name Type Attributes Default Description
array Array The array of grouped elements to process.
iteratee function <optional>
_.identity The function to combine regrouped values.
Since:
  • 3.8.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]

_.unzipWith(zipped, _.add);
// => [3, 30, 300]

(static) unzipWith(array, iterateeopt) → {Array}

This method is like `_.unzip` except that it accepts `iteratee` to specify how regrouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Parameters:
Name Type Attributes Default Description
array Array The array of grouped elements to process.
iteratee function <optional>
_.identity The function to combine regrouped values.
Since:
  • 3.8.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]

_.unzipWith(zipped, _.add);
// => [3, 30, 300]

(static) update(object, path, updater) → {Object}

This method is like `_.set` except that accepts `updater` to produce the value to set. Use `_.updateWith` to customize `path` creation. The `updater` is invoked with one argument: (value). **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// => 9

_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// => 0

(static) update(object, path, updater) → {Object}

This method is like `_.set` except that accepts `updater` to produce the value to set. Use `_.updateWith` to customize `path` creation. The `updater` is invoked with one argument: (value). **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// => 9

_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// => 0

(static) updateWith(object, path, updater, customizeropt) → {Object}

This method is like `_.update` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.updateWith(object, '[0][1]', _.constant('a'), Object);
// => { '0': { '1': 'a' } }

(static) updateWith(object, path, updater, customizeropt) → {Object}

This method is like `_.update` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.updateWith(object, '[0][1]', _.constant('a'), Object);
// => { '0': { '1': 'a' } }

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) valuesIn(object) → {Array}

Creates an array of the own and inherited enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)

(static) valuesIn(object) → {Array}

Creates an array of the own and inherited enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)

(static) words(stringopt, patternopt) → {Array}

Splits `string` into an array of its words.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
pattern RegExp | string <optional>
The pattern to match words.
Since:
  • 3.0.0
Source:
Returns:
Returns the words of `string`.
Type
Array
Example
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']

_.words('fred, barney, & pebbles', /[^, ]+/g);
// => ['fred', 'barney', '&', 'pebbles']

(static) words(stringopt, patternopt) → {Array}

Splits `string` into an array of its words.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
pattern RegExp | string <optional>
The pattern to match words.
Since:
  • 3.0.0
Source:
Returns:
Returns the words of `string`.
Type
Array
Example
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']

_.words('fred, barney, & pebbles', /[^, ]+/g);
// => ['fred', 'barney', '&', 'pebbles']

(static) wrap(value, wrapperopt) → {function}

Creates a function that provides `value` to `wrapper` as its first argument. Any additional arguments provided to the function are appended to those provided to the `wrapper`. The wrapper is invoked with the `this` binding of the created function.
Parameters:
Name Type Attributes Default Description
value * The value to wrap.
wrapper function <optional>
identity The wrapper function.
Since:
  • 0.1.0
Source:
Returns:
Returns the new function.
Type
function
Example
var p = _.wrap(_.escape, function(func, text) {
  return '<p>' + func(text) + '</p>';
});

p('fred, barney, & pebbles');
// => '<p>fred, barney, &amp; pebbles</p>'

(static) wrap(value, wrapperopt) → {function}

Creates a function that provides `value` to `wrapper` as its first argument. Any additional arguments provided to the function are appended to those provided to the `wrapper`. The wrapper is invoked with the `this` binding of the created function.
Parameters:
Name Type Attributes Default Description
value * The value to wrap.
wrapper function <optional>
identity The wrapper function.
Since:
  • 0.1.0
Source:
Returns:
Returns the new function.
Type
function
Example
var p = _.wrap(_.escape, function(func, text) {
  return '<p>' + func(text) + '</p>';
});

p('fred, barney, & pebbles');
// => '<p>fred, barney, &amp; pebbles</p>'

(static) zipObject(propsopt, valuesopt) → {Object}

This method is like `_.fromPairs` except that it accepts two arrays, one of property identifiers and one of corresponding values.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 0.4.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }

(static) zipObject(propsopt, valuesopt) → {Object}

This method is like `_.fromPairs` except that it accepts two arrays, one of property identifiers and one of corresponding values.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 0.4.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }

(static) zipObjectDeep(propsopt, valuesopt) → {Object}

This method is like `_.zipObject` except that it supports property paths.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 4.1.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }

(static) zipObjectDeep(propsopt, valuesopt) → {Object}

This method is like `_.zipObject` except that it supports property paths.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 4.1.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }

_(value) → {Object}

new _(value) → {Object}

Creates a `lodash` object which wraps `value` to enable implicit method chain sequences. Methods that operate on and return arrays, collections, and functions can be chained together. Methods that retrieve a single value or may return a primitive value will automatically end the chain sequence and return the unwrapped value. Otherwise, the value must be unwrapped with `_#value`. Explicit chain sequences, which must be unwrapped with `_#value`, may be enabled using `_.chain`. The execution of chained methods is lazy, that is, it's deferred until `_#value` is implicitly or explicitly called. Lazy evaluation allows several methods to support shortcut fusion. Shortcut fusion is an optimization to merge iteratee calls; this avoids the creation of intermediate arrays and can greatly reduce the number of iteratee executions. Sections of a chain sequence qualify for shortcut fusion if the section is applied to an array and iteratees accept only one argument. The heuristic for whether a section qualifies for shortcut fusion is subject to change. Chaining is supported in custom builds as long as the `_#value` method is directly or indirectly included in the build. In addition to lodash methods, wrappers have `Array` and `String` methods. The wrapper `Array` methods are: `concat`, `join`, `pop`, `push`, `shift`, `sort`, `splice`, and `unshift` The wrapper `String` methods are: `replace` and `split` The wrapper methods that support shortcut fusion are: `at`, `compact`, `drop`, `dropRight`, `dropWhile`, `filter`, `find`, `findLast`, `head`, `initial`, `last`, `map`, `reject`, `reverse`, `slice`, `tail`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, and `toArray` The chainable wrapper methods are: `after`, `ary`, `assign`, `assignIn`, `assignInWith`, `assignWith`, `at`, `before`, `bind`, `bindAll`, `bindKey`, `castArray`, `chain`, `chunk`, `commit`, `compact`, `concat`, `conforms`, `constant`, `countBy`, `create`, `curry`, `debounce`, `defaults`, `defaultsDeep`, `defer`, `delay`, `difference`, `differenceBy`, `differenceWith`, `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `extend`, `extendWith`, `fill`, `filter`, `flatMap`, `flatMapDeep`, `flatMapDepth`, `flatten`, `flattenDeep`, `flattenDepth`, `flip`, `flow`, `flowRight`, `fromPairs`, `functions`, `functionsIn`, `groupBy`, `initial`, `intersection`, `intersectionBy`, `intersectionWith`, `invert`, `invertBy`, `invokeMap`, `iteratee`, `keyBy`, `keys`, `keysIn`, `map`, `mapKeys`, `mapValues`, `matches`, `matchesProperty`, `memoize`, `merge`, `mergeWith`, `method`, `methodOf`, `mixin`, `negate`, `nthArg`, `omit`, `omitBy`, `once`, `orderBy`, `over`, `overArgs`, `overEvery`, `overSome`, `partial`, `partialRight`, `partition`, `pick`, `pickBy`, `plant`, `property`, `propertyOf`, `pull`, `pullAll`, `pullAllBy`, `pullAllWith`, `pullAt`, `push`, `range`, `rangeRight`, `rearg`, `reject`, `remove`, `rest`, `reverse`, `sampleSize`, `set`, `setWith`, `shuffle`, `slice`, `sort`, `sortBy`, `splice`, `spread`, `tail`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, `tap`, `throttle`, `thru`, `toArray`, `toPairs`, `toPairsIn`, `toPath`, `toPlainObject`, `transform`, `unary`, `union`, `unionBy`, `unionWith`, `uniq`, `uniqBy`, `uniqWith`, `unset`, `unshift`, `unzip`, `unzipWith`, `update`, `updateWith`, `values`, `valuesIn`, `without`, `wrap`, `xor`, `xorBy`, `xorWith`, `zip`, `zipObject`, `zipObjectDeep`, and `zipWith` The wrapper methods that are **not** chainable by default are: `add`, `attempt`, `camelCase`, `capitalize`, `ceil`, `clamp`, `clone`, `cloneDeep`, `cloneDeepWith`, `cloneWith`, `conformsTo`, `deburr`, `defaultTo`, `divide`, `each`, `eachRight`, `endsWith`, `eq`, `escape`, `escapeRegExp`, `every`, `find`, `findIndex`, `findKey`, `findLast`, `findLastIndex`, `findLastKey`, `first`, `floor`, `forEach`, `forEachRight`, `forIn`, `forInRight`, `forOwn`, `forOwnRight`, `get`, `gt`, `gte`, `has`, `hasIn`, `head`, `identity`, `includes`, `indexOf`, `inRange`, `invoke`, `isArguments`, `isArray`, `isArrayBuffer`, `isArrayLike`, `isArrayLikeObject`, `isBoolean`, `isBuffer`, `isDate`, `isElement`, `isEmpty`, `isEqual`, `isEqualWith`, `isError`, `isFinite`, `isFunction`, `isInteger`, `isLength`, `isMap`, `isMatch`, `isMatchWith`, `isNaN`, `isNative`, `isNil`, `isNull`, `isNumber`, `isObject`, `isObjectLike`, `isPlainObject`, `isRegExp`, `isSafeInteger`, `isSet`, `isString`, `isUndefined`, `isTypedArray`, `isWeakMap`, `isWeakSet`, `join`, `kebabCase`, `last`, `lastIndexOf`, `lowerCase`, `lowerFirst`, `lt`, `lte`, `max`, `maxBy`, `mean`, `meanBy`, `min`, `minBy`, `multiply`, `noConflict`, `noop`, `now`, `nth`, `pad`, `padEnd`, `padStart`, `parseInt`, `pop`, `random`, `reduce`, `reduceRight`, `repeat`, `result`, `round`, `runInContext`, `sample`, `shift`, `size`, `snakeCase`, `some`, `sortedIndex`, `sortedIndexBy`, `sortedLastIndex`, `sortedLastIndexBy`, `startCase`, `startsWith`, `stubArray`, `stubFalse`, `stubObject`, `stubString`, `stubTrue`, `subtract`, `sum`, `sumBy`, `template`, `times`, `toFinite`, `toInteger`, `toJSON`, `toLength`, `toLower`, `toNumber`, `toSafeInteger`, `toString`, `toUpper`, `trim`, `trimEnd`, `trimStart`, `truncate`, `unescape`, `uniqueId`, `upperCase`, `upperFirst`, `value`, and `words`
Parameters:
Name Type Description
value * The value to wrap in a `lodash` instance.
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2, 3]);

// Returns an unwrapped value.
wrapped.reduce(_.add);
// => 6

// Returns a wrapped value.
var squares = wrapped.map(square);

_.isArray(squares);
// => false

_.isArray(squares.value());
// => true

Members

(static) add

Adds two numbers.
Since:
  • 3.4.0
Source:
Example
_.add(6, 4);
// => 10

(static) add

Adds two numbers.
Since:
  • 3.4.0
Source:
Example
_.add(6, 4);
// => 10

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assignWith

This method is like `_.assign` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
  • _.assignInWith
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) assignWith

This method is like `_.assign` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
  • _.assignInWith
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) at

Creates an array of values corresponding to `paths` of `object`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_.at(object, ['a[0].b.c', 'a[1]']);
// => [3, 4]

(static) at

This method is the wrapper version of `_.at`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]

(static) at

Creates an array of values corresponding to `paths` of `object`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_.at(object, ['a[0].b.c', 'a[1]']);
// => [3, 4]

(static) at

This method is the wrapper version of `_.at`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]

(static) attempt

Attempts to invoke `func`, returning either the result or the caught error object. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 3.0.0
Source:
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
  return document.querySelectorAll(selector);
}, '>_>');

if (_.isError(elements)) {
  elements = [];
}

(static) attempt

Attempts to invoke `func`, returning either the result or the caught error object. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 3.0.0
Source:
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
  return document.querySelectorAll(selector);
}, '>_>');

if (_.isError(elements)) {
  elements = [];
}

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bindAll

Binds methods of an object to the object itself, overwriting the existing method. **Note:** This method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
var view = {
  'label': 'docs',
  'click': function() {
    console.log('clicked ' + this.label);
  }
};

_.bindAll(view, ['click']);
jQuery(element).on('click', view.click);
// => Logs 'clicked docs' when clicked.

(static) bindAll

Binds methods of an object to the object itself, overwriting the existing method. **Note:** This method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
var view = {
  'label': 'docs',
  'click': function() {
    console.log('clicked ' + this.label);
  }
};

_.bindAll(view, ['click']);
jQuery(element).on('click', view.click);
// => Logs 'clicked docs' when clicked.

(static) bindKey

Creates a function that invokes the method at `object[key]` with `partials` prepended to the arguments it receives. This method differs from `_.bind` by allowing bound functions to reference methods that may be redefined or don't yet exist. See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern) for more details. The `_.bindKey.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments.
Since:
  • 0.10.0
Source:
Example
var object = {
  'user': 'fred',
  'greet': function(greeting, punctuation) {
    return greeting + ' ' + this.user + punctuation;
  }
};

var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// => 'hi fred!'

object.greet = function(greeting, punctuation) {
  return greeting + 'ya ' + this.user + punctuation;
};

bound('!');
// => 'hiya fred!'

// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// => 'hiya fred!'

(static) bindKey

Creates a function that invokes the method at `object[key]` with `partials` prepended to the arguments it receives. This method differs from `_.bind` by allowing bound functions to reference methods that may be redefined or don't yet exist. See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern) for more details. The `_.bindKey.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments.
Since:
  • 0.10.0
Source:
Example
var object = {
  'user': 'fred',
  'greet': function(greeting, punctuation) {
    return greeting + ' ' + this.user + punctuation;
  }
};

var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// => 'hi fred!'

object.greet = function(greeting, punctuation) {
  return greeting + 'ya ' + this.user + punctuation;
};

bound('!');
// => 'hiya fred!'

// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// => 'hiya fred!'

(static) camelCase

Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
Since:
  • 3.0.0
Source:
Example
_.camelCase('Foo Bar');
// => 'fooBar'

_.camelCase('--foo-bar--');
// => 'fooBar'

_.camelCase('__FOO_BAR__');
// => 'fooBar'

(static) camelCase

Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
Since:
  • 3.0.0
Source:
Example
_.camelCase('Foo Bar');
// => 'fooBar'

_.camelCase('--foo-bar--');
// => 'fooBar'

_.camelCase('__FOO_BAR__');
// => 'fooBar'

(static) ceil

Computes `number` rounded up to `precision`.
Since:
  • 3.10.0
Source:
Example
_.ceil(4.006);
// => 5

_.ceil(6.004, 2);
// => 6.01

_.ceil(6040, -2);
// => 6100

(static) ceil

Computes `number` rounded up to `precision`.
Since:
  • 3.10.0
Source:
Example
_.ceil(4.006);
// => 5

_.ceil(6.004, 2);
// => 6.01

_.ceil(6040, -2);
// => 6100

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) commit

Executes the chain sequence and returns the wrapped result.
Since:
  • 3.2.0
Source:
Example
var array = [1, 2];
var wrapped = _(array).push(3);

console.log(array);
// => [1, 2]

wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]

wrapped.last();
// => 3

console.log(array);
// => [1, 2, 3]

(static) commit

Executes the chain sequence and returns the wrapped result.
Since:
  • 3.2.0
Source:
Example
var array = [1, 2];
var wrapped = _(array).push(3);

console.log(array);
// => [1, 2]

wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]

wrapped.last();
// => 3

console.log(array);
// => [1, 2, 3]

(static) countBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the number of times the key was returned by `iteratee`. The iteratee is invoked with one argument: (value).
Since:
  • 0.5.0
Source:
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }

// The `_.property` iteratee shorthand.
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }

(static) countBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the number of times the key was returned by `iteratee`. The iteratee is invoked with one argument: (value).
Since:
  • 0.5.0
Source:
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }

// The `_.property` iteratee shorthand.
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaultsDeep

This method is like `_.defaults` except that it recursively assigns default properties. **Note:** This method mutates `object`.
Since:
  • 3.10.0
Source:
See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } });
// => { 'a': { 'b': 2, 'c': 3 } }

(static) defaultsDeep

This method is like `_.defaults` except that it recursively assigns default properties. **Note:** This method mutates `object`.
Since:
  • 3.10.0
Source:
See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } });
// => { 'a': { 'b': 2, 'c': 3 } }

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) difference

Creates an array of `array` values not included in the other given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array. **Note:** Unlike `_.pullAll`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.without, _.xor
Example
_.difference([2, 1], [2, 3]);
// => [1]

(static) difference

Creates an array of `array` values not included in the other given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array. **Note:** Unlike `_.pullAll`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.without, _.xor
Example
_.difference([2, 1], [2, 3]);
// => [1]

(static) differenceBy

This method is like `_.difference` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.pullAllBy`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2]

// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) differenceBy

This method is like `_.difference` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.pullAllBy`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2]

// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) differenceWith

This method is like `_.difference` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.pullAllWith`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];

_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

(static) differenceWith

This method is like `_.difference` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.pullAllWith`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];

_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

(static) divide

Divide two numbers.
Since:
  • 4.7.0
Source:
Example
_.divide(6, 4);
// => 1.5

(static) divide

Divide two numbers.
Since:
  • 4.7.0
Source:
Example
_.divide(6, 4);
// => 1.5

(static) entries

Creates an array of own enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)

(static) entries

Creates an array of own enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)

(static) entriesIn

Creates an array of own and inherited enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)

(static) entriesIn

Creates an array of own and inherited enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extendWith

This method is like `_.assignIn` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignInWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) extendWith

This method is like `_.assignIn` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignInWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) findLast

This method is like `_.find` except that it iterates over elements of `collection` from right to left.
Since:
  • 2.0.0
Source:
Example
_.findLast([1, 2, 3, 4], function(n) {
  return n % 2 == 1;
});
// => 3

(static) findLast

This method is like `_.find` except that it iterates over elements of `collection` from right to left.
Since:
  • 2.0.0
Source:
Example
_.findLast([1, 2, 3, 4], function(n) {
  return n % 2 == 1;
});
// => 3

(static) floor

Computes `number` rounded down to `precision`.
Since:
  • 3.10.0
Source:
Example
_.floor(4.006);
// => 4

_.floor(0.046, 2);
// => 0.04

_.floor(4060, -2);
// => 4000

(static) floor

Computes `number` rounded down to `precision`.
Since:
  • 3.10.0
Source:
Example
_.floor(4.006);
// => 4

_.floor(0.046, 2);
// => 0.04

_.floor(4060, -2);
// => 4000

(static) flow

Creates a function that returns the result of invoking the given functions with the `this` binding of the created function, where each successive invocation is supplied the return value of the previous.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flow([_.add, square]);
addSquare(1, 2);
// => 9

(static) flow

Creates a function that returns the result of invoking the given functions with the `this` binding of the created function, where each successive invocation is supplied the return value of the previous.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flow([_.add, square]);
addSquare(1, 2);
// => 9

(static) flowRight

This method is like `_.flow` except that it creates a function that invokes the given functions from right to left.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flowRight([square, _.add]);
addSquare(1, 2);
// => 9

(static) flowRight

This method is like `_.flow` except that it creates a function that invokes the given functions from right to left.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flowRight([square, _.add]);
addSquare(1, 2);
// => 9

(static) groupBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }

// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

(static) groupBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }

// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

(static) gt

Checks if `value` is greater than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gt(3, 1);
// => true

_.gt(3, 3);
// => false

_.gt(1, 3);
// => false

(static) gt

Checks if `value` is greater than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gt(3, 1);
// => true

_.gt(3, 3);
// => false

_.gt(1, 3);
// => false

(static) gte

Checks if `value` is greater than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gte(3, 1);
// => true

_.gte(3, 3);
// => true

_.gte(1, 3);
// => false

(static) gte

Checks if `value` is greater than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gte(3, 1);
// => true

_.gte(3, 3);
// => true

_.gte(1, 3);
// => false

(static) intersection

Creates an array of unique values that are included in all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array.
Since:
  • 0.1.0
Source:
Example
_.intersection([2, 1], [2, 3]);
// => [2]

(static) intersection

Creates an array of unique values that are included in all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array.
Since:
  • 0.1.0
Source:
Example
_.intersection([2, 1], [2, 3]);
// => [2]

(static) intersectionBy

This method is like `_.intersection` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [2.1]

// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }]

(static) intersectionBy

This method is like `_.intersection` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [2.1]

// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }]

(static) intersectionWith

This method is like `_.intersection` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.intersectionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }]

(static) intersectionWith

This method is like `_.intersection` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.intersectionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }]

(static) invert

Creates an object composed of the inverted keys and values of `object`. If `object` contains duplicate values, subsequent values overwrite property assignments of previous values.
Since:
  • 0.7.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invert(object);
// => { '1': 'c', '2': 'b' }

(static) invert

Creates an object composed of the inverted keys and values of `object`. If `object` contains duplicate values, subsequent values overwrite property assignments of previous values.
Since:
  • 0.7.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invert(object);
// => { '1': 'c', '2': 'b' }

(static) invertBy

This method is like `_.invert` except that the inverted object is generated from the results of running each element of `object` thru `iteratee`. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. The iteratee is invoked with one argument: (value).
Since:
  • 4.1.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }

_.invertBy(object, function(value) {
  return 'group' + value;
});
// => { 'group1': ['a', 'c'], 'group2': ['b'] }

(static) invertBy

This method is like `_.invert` except that the inverted object is generated from the results of running each element of `object` thru `iteratee`. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. The iteratee is invoked with one argument: (value).
Since:
  • 4.1.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }

_.invertBy(object, function(value) {
  return 'group' + value;
});
// => { 'group1': ['a', 'c'], 'group2': ['b'] }

(static) invoke

Invokes the method at `path` of `object`.
Since:
  • 4.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };

_.invoke(object, 'a[0].b.c.slice', 1, 3);
// => [2, 3]

(static) invoke

Invokes the method at `path` of `object`.
Since:
  • 4.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };

_.invoke(object, 'a[0].b.c.slice', 1, 3);
// => [2, 3]

(static) invokeMap

Invokes the method at `path` of each element in `collection`, returning an array of the results of each invoked method. Any additional arguments are provided to each invoked method. If `path` is a function, it's invoked for, and `this` bound to, each element in `collection`.
Since:
  • 4.0.0
Source:
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]

_.invokeMap([123, 456], String.prototype.split, '');
// => [['1', '2', '3'], ['4', '5', '6']]

(static) invokeMap

Invokes the method at `path` of each element in `collection`, returning an array of the results of each invoked method. Any additional arguments are provided to each invoked method. If `path` is a function, it's invoked for, and `this` bound to, each element in `collection`.
Since:
  • 4.0.0
Source:
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]

_.invokeMap([123, 456], String.prototype.split, '');
// => [['1', '2', '3'], ['4', '5', '6']]

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray :function

Checks if `value` is classified as an `Array` object.
Type:
  • function
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArrayBuffer

Checks if `value` is classified as an `ArrayBuffer` object.
Since:
  • 4.3.0
Source:
Example
_.isArrayBuffer(new ArrayBuffer(2));
// => true

_.isArrayBuffer(new Array(2));
// => false

(static) isArrayBuffer

Checks if `value` is classified as an `ArrayBuffer` object.
Since:
  • 4.3.0
Source:
Example
_.isArrayBuffer(new ArrayBuffer(2));
// => true

_.isArrayBuffer(new Array(2));
// => false

(static) isBuffer

Checks if `value` is a buffer.
Since:
  • 4.3.0
Source:
Example
_.isBuffer(new Buffer(2));
// => true

_.isBuffer(new Uint8Array(2));
// => false

(static) isBuffer

Checks if `value` is a buffer.
Since:
  • 4.3.0
Source:
Example
_.isBuffer(new Buffer(2));
// => true

_.isBuffer(new Uint8Array(2));
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isMap

Checks if `value` is classified as a `Map` object.
Since:
  • 4.3.0
Source:
Example
_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false

(static) isMap

Checks if `value` is classified as a `Map` object.
Since:
  • 4.3.0
Source:
Example
_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isSet

Checks if `value` is classified as a `Set` object.
Since:
  • 4.3.0
Source:
Example
_.isSet(new Set);
// => true

_.isSet(new WeakSet);
// => false

(static) isSet

Checks if `value` is classified as a `Set` object.
Since:
  • 4.3.0
Source:
Example
_.isSet(new Set);
// => true

_.isSet(new WeakSet);
// => false

(static) isTypedArray

Checks if `value` is classified as a typed array.
Since:
  • 3.0.0
Source:
Example
_.isTypedArray(new Uint8Array);
// => true

_.isTypedArray([]);
// => false

(static) isTypedArray

Checks if `value` is classified as a typed array.
Since:
  • 3.0.0
Source:
Example
_.isTypedArray(new Uint8Array);
// => true

_.isTypedArray([]);
// => false

(static) iteratee

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Since:
  • 4.0.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) kebabCase

Converts `string` to [kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).
Since:
  • 3.0.0
Source:
Example
_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'

(static) kebabCase

Converts `string` to [kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).
Since:
  • 3.0.0
Source:
Example
_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'

(static) keyBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the last element responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
var array = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

_.keyBy(array, function(o) {
  return String.fromCharCode(o.code);
});
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }

_.keyBy(array, 'dir');
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }

(static) keyBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the last element responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
var array = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

_.keyBy(array, function(o) {
  return String.fromCharCode(o.code);
});
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }

_.keyBy(array, 'dir');
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }

(static) keys

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Since:
  • 0.1.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keysIn

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Since:
  • 3.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) lowerCase

Converts `string`, as space separated words, to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerCase('--Foo-Bar--');
// => 'foo bar'

_.lowerCase('fooBar');
// => 'foo bar'

_.lowerCase('__FOO_BAR__');
// => 'foo bar'

(static) lowerCase

Converts `string`, as space separated words, to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerCase('--Foo-Bar--');
// => 'foo bar'

_.lowerCase('fooBar');
// => 'foo bar'

_.lowerCase('__FOO_BAR__');
// => 'foo bar'

(static) lowerFirst

Converts the first character of `string` to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

(static) lowerFirst

Converts the first character of `string` to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

(static) lt

Checks if `value` is less than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lt(1, 3);
// => true

_.lt(3, 3);
// => false

_.lt(3, 1);
// => false

(static) lt

Checks if `value` is less than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lt(1, 3);
// => true

_.lt(3, 3);
// => false

_.lt(3, 1);
// => false

(static) lte

Checks if `value` is less than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lte(1, 3);
// => true

_.lte(3, 3);
// => true

_.lte(3, 1);
// => false

(static) lte

Checks if `value` is less than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lte(1, 3);
// => true

_.lte(3, 3);
// => true

_.lte(3, 1);
// => false

(static) merge

This method is like `_.assign` except that it recursively merges own and inherited enumerable string keyed properties of source objects into the destination object. Source properties that resolve to `undefined` are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object`.
Since:
  • 0.5.0
Source:
Example
var object = {
  'a': [{ 'b': 2 }, { 'd': 4 }]
};

var other = {
  'a': [{ 'c': 3 }, { 'e': 5 }]
};

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }

(static) merge

This method is like `_.assign` except that it recursively merges own and inherited enumerable string keyed properties of source objects into the destination object. Source properties that resolve to `undefined` are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object`.
Since:
  • 0.5.0
Source:
Example
var object = {
  'a': [{ 'b': 2 }, { 'd': 4 }]
};

var other = {
  'a': [{ 'c': 3 }, { 'e': 5 }]
};

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }

(static) mergeWith

This method is like `_.merge` except that it accepts `customizer` which is invoked to produce the merged values of the destination and source properties. If `customizer` returns `undefined`, merging is handled by the method instead. The `customizer` is invoked with six arguments: (objValue, srcValue, key, object, source, stack). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
Example
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }

(static) mergeWith

This method is like `_.merge` except that it accepts `customizer` which is invoked to produce the merged values of the destination and source properties. If `customizer` returns `undefined`, merging is handled by the method instead. The `customizer` is invoked with six arguments: (objValue, srcValue, key, object, source, stack). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
Example
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }

(static) method

Creates a function that invokes the method at `path` of a given object. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var objects = [
  { 'a': { 'b': _.constant(2) } },
  { 'a': { 'b': _.constant(1) } }
];

_.map(objects, _.method('a.b'));
// => [2, 1]

_.map(objects, _.method(['a', 'b']));
// => [2, 1]

(static) method

Creates a function that invokes the method at `path` of a given object. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var objects = [
  { 'a': { 'b': _.constant(2) } },
  { 'a': { 'b': _.constant(1) } }
];

_.map(objects, _.method('a.b'));
// => [2, 1]

_.map(objects, _.method(['a', 'b']));
// => [2, 1]

(static) methodOf

The opposite of `_.method`; this method creates a function that invokes the method at a given path of `object`. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var array = _.times(3, _.constant),
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.methodOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// => [2, 0]

(static) methodOf

The opposite of `_.method`; this method creates a function that invokes the method at a given path of `object`. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var array = _.times(3, _.constant),
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.methodOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// => [2, 0]

(static) multiply

Multiply two numbers.
Since:
  • 4.7.0
Source:
Example
_.multiply(6, 4);
// => 24

(static) multiply

Multiply two numbers.
Since:
  • 4.7.0
Source:
Example
_.multiply(6, 4);
// => 24

(static) next

Gets the next value on a wrapped object following the [iterator protocol](https://mdn.io/iteration_protocols#iterator).
Since:
  • 4.0.0
Source:
Example
var wrapped = _([1, 2]);

wrapped.next();
// => { 'done': false, 'value': 1 }

wrapped.next();
// => { 'done': false, 'value': 2 }

wrapped.next();
// => { 'done': true, 'value': undefined }

(static) next

Gets the next value on a wrapped object following the [iterator protocol](https://mdn.io/iteration_protocols#iterator).
Since:
  • 4.0.0
Source:
Example
var wrapped = _([1, 2]);

wrapped.next();
// => { 'done': false, 'value': 1 }

wrapped.next();
// => { 'done': false, 'value': 2 }

wrapped.next();
// => { 'done': true, 'value': undefined }

(static) now

Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
Since:
  • 2.4.0
Source:
Example
_.defer(function(stamp) {
  console.log(_.now() - stamp);
}, _.now());
// => Logs the number of milliseconds it took for the deferred invocation.

(static) omit

The opposite of `_.pick`; this method creates an object composed of the own and inherited enumerable property paths of `object` that are not omitted. **Note:** This method is considerably slower than `_.pick`.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);
// => { 'b': '2' }

(static) omit

The opposite of `_.pick`; this method creates an object composed of the own and inherited enumerable property paths of `object` that are not omitted. **Note:** This method is considerably slower than `_.pick`.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);
// => { 'b': '2' }

(static) over

Creates a function that invokes `iteratees` with the arguments it receives and returns their results.
Since:
  • 4.0.0
Source:
Example
var func = _.over([Math.max, Math.min]);

func(1, 2, 3, 4);
// => [4, 1]

(static) over

Creates a function that invokes `iteratees` with the arguments it receives and returns their results.
Since:
  • 4.0.0
Source:
Example
var func = _.over([Math.max, Math.min]);

func(1, 2, 3, 4);
// => [4, 1]

(static) overArgs

Creates a function that invokes `func` with its arguments transformed.
Since:
  • 4.0.0
Source:
Example
function doubled(n) {
  return n * 2;
}

function square(n) {
  return n * n;
}

var func = _.overArgs(function(x, y) {
  return [x, y];
}, [square, doubled]);

func(9, 3);
// => [81, 6]

func(10, 5);
// => [100, 10]

(static) overArgs

Creates a function that invokes `func` with its arguments transformed.
Since:
  • 4.0.0
Source:
Example
function doubled(n) {
  return n * 2;
}

function square(n) {
  return n * n;
}

var func = _.overArgs(function(x, y) {
  return [x, y];
}, [square, doubled]);

func(9, 3);
// => [81, 6]

func(10, 5);
// => [100, 10]

(static) overEvery

Creates a function that checks if **all** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overEvery([Boolean, isFinite]);

func('1');
// => true

func(null);
// => false

func(NaN);
// => false

(static) overEvery

Creates a function that checks if **all** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overEvery([Boolean, isFinite]);

func('1');
// => true

func(null);
// => false

func(NaN);
// => false

(static) overSome

Creates a function that checks if **any** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overSome([Boolean, isFinite]);

func('1');
// => true

func(null);
// => true

func(NaN);
// => false

var matchesFunc = _.overSome([{ 'a': 1 }, { 'a': 2 }])
var matchesPropertyFunc = _.overSome([['a', 1], ['a', 2]])

(static) overSome

Creates a function that checks if **any** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overSome([Boolean, isFinite]);

func('1');
// => true

func(null);
// => true

func(NaN);
// => false

var matchesFunc = _.overSome([{ 'a': 1 }, { 'a': 2 }])
var matchesPropertyFunc = _.overSome([['a', 1], ['a', 2]])

(static) partial

Creates a function that invokes `func` with `partials` prepended to the arguments it receives. This method is like `_.bind` except it does **not** alter the `this` binding. The `_.partial.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 0.2.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'

// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'

(static) partial

Creates a function that invokes `func` with `partials` prepended to the arguments it receives. This method is like `_.bind` except it does **not** alter the `this` binding. The `_.partial.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 0.2.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'

// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'

(static) partialRight

This method is like `_.partial` except that partially applied arguments are appended to the arguments it receives. The `_.partialRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 1.0.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'

// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'

(static) partialRight

This method is like `_.partial` except that partially applied arguments are appended to the arguments it receives. The `_.partialRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 1.0.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'

// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'

(static) partition

Creates an array of elements split into two groups, the first of which contains elements `predicate` returns truthy for, the second of which contains elements `predicate` returns falsey for. The predicate is invoked with one argument: (value).
Since:
  • 3.0.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': false },
  { 'user': 'fred',    'age': 40, 'active': true },
  { 'user': 'pebbles', 'age': 1,  'active': false }
];

_.partition(users, function(o) { return o.active; });
// => objects for [['fred'], ['barney', 'pebbles']]

// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// => objects for [['pebbles'], ['barney', 'fred']]

// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// => objects for [['barney', 'pebbles'], ['fred']]

// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// => objects for [['fred'], ['barney', 'pebbles']]

(static) partition

Creates an array of elements split into two groups, the first of which contains elements `predicate` returns truthy for, the second of which contains elements `predicate` returns falsey for. The predicate is invoked with one argument: (value).
Since:
  • 3.0.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': false },
  { 'user': 'fred',    'age': 40, 'active': true },
  { 'user': 'pebbles', 'age': 1,  'active': false }
];

_.partition(users, function(o) { return o.active; });
// => objects for [['fred'], ['barney', 'pebbles']]

// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// => objects for [['pebbles'], ['barney', 'fred']]

// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// => objects for [['barney', 'pebbles'], ['fred']]

// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// => objects for [['fred'], ['barney', 'pebbles']]

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) plant

Creates a clone of the chain sequence planting `value` as the wrapped value.
Since:
  • 3.2.0
Source:
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);

other.value();
// => [9, 16]

wrapped.value();
// => [1, 4]

(static) plant

Creates a clone of the chain sequence planting `value` as the wrapped value.
Since:
  • 3.2.0
Source:
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);

other.value();
// => [9, 16]

wrapped.value();
// => [1, 4]

(static) pull

Removes all given values from `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.without`, this method mutates `array`. Use `_.remove` to remove elements from an array by predicate.
Since:
  • 2.0.0
Source:
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pull(array, 'a', 'c');
console.log(array);
// => ['b', 'b']

(static) pull

Removes all given values from `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.without`, this method mutates `array`. Use `_.remove` to remove elements from an array by predicate.
Since:
  • 2.0.0
Source:
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pull(array, 'a', 'c');
console.log(array);
// => ['b', 'b']

(static) pullAt

Removes elements from `array` corresponding to `indexes` and returns an array of removed elements. **Note:** Unlike `_.at`, this method mutates `array`.
Since:
  • 3.0.0
Source:
Example
var array = ['a', 'b', 'c', 'd'];
var pulled = _.pullAt(array, [1, 3]);

console.log(array);
// => ['a', 'c']

console.log(pulled);
// => ['b', 'd']

(static) pullAt

Removes elements from `array` corresponding to `indexes` and returns an array of removed elements. **Note:** Unlike `_.at`, this method mutates `array`.
Since:
  • 3.0.0
Source:
Example
var array = ['a', 'b', 'c', 'd'];
var pulled = _.pullAt(array, [1, 3]);

console.log(array);
// => ['a', 'c']

console.log(pulled);
// => ['b', 'd']

(static) range

Creates an array of numbers (positive and/or negative) progressing from `start` up to, but not including, `end`. A step of `-1` is used if a negative `start` is specified without an `end` or `step`. If `end` is not specified, it's set to `start` with `start` then set to `0`. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Since:
  • 0.1.0
Source:
See:
  • _.inRange, _.rangeRight
Example
_.range(4);
// => [0, 1, 2, 3]

_.range(-4);
// => [0, -1, -2, -3]

_.range(1, 5);
// => [1, 2, 3, 4]

_.range(0, 20, 5);
// => [0, 5, 10, 15]

_.range(0, -4, -1);
// => [0, -1, -2, -3]

_.range(1, 4, 0);
// => [1, 1, 1]

_.range(0);
// => []

(static) range

Creates an array of numbers (positive and/or negative) progressing from `start` up to, but not including, `end`. A step of `-1` is used if a negative `start` is specified without an `end` or `step`. If `end` is not specified, it's set to `start` with `start` then set to `0`. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Since:
  • 0.1.0
Source:
See:
  • _.inRange, _.rangeRight
Example
_.range(4);
// => [0, 1, 2, 3]

_.range(-4);
// => [0, -1, -2, -3]

_.range(1, 5);
// => [1, 2, 3, 4]

_.range(0, 20, 5);
// => [0, 5, 10, 15]

_.range(0, -4, -1);
// => [0, -1, -2, -3]

_.range(1, 4, 0);
// => [1, 1, 1]

_.range(0);
// => []

(static) rangeRight

This method is like `_.range` except that it populates values in descending order.
Since:
  • 4.0.0
Source:
See:
  • _.inRange, _.range
Example
_.rangeRight(4);
// => [3, 2, 1, 0]

_.rangeRight(-4);
// => [-3, -2, -1, 0]

_.rangeRight(1, 5);
// => [4, 3, 2, 1]

_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]

_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]

_.rangeRight(1, 4, 0);
// => [1, 1, 1]

_.rangeRight(0);
// => []

(static) rangeRight

This method is like `_.range` except that it populates values in descending order.
Since:
  • 4.0.0
Source:
See:
  • _.inRange, _.range
Example
_.rangeRight(4);
// => [3, 2, 1, 0]

_.rangeRight(-4);
// => [-3, -2, -1, 0]

_.rangeRight(1, 5);
// => [4, 3, 2, 1]

_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]

_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]

_.rangeRight(1, 4, 0);
// => [1, 1, 1]

_.rangeRight(0);
// => []

(static) rearg

Creates a function that invokes `func` with arguments arranged according to the specified `indexes` where the argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on.
Since:
  • 3.0.0
Source:
Example
var rearged = _.rearg(function(a, b, c) {
  return [a, b, c];
}, [2, 0, 1]);

rearged('b', 'c', 'a')
// => ['a', 'b', 'c']

(static) rearg

Creates a function that invokes `func` with arguments arranged according to the specified `indexes` where the argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on.
Since:
  • 3.0.0
Source:
Example
var rearged = _.rearg(function(a, b, c) {
  return [a, b, c];
}, [2, 0, 1]);

rearged('b', 'c', 'a')
// => ['a', 'b', 'c']

(static) reverse

This method is the wrapper version of `_.reverse`. **Note:** This method mutates the wrapped array.
Since:
  • 0.1.0
Source:
Example
var array = [1, 2, 3];

_(array).reverse().value()
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) reverse

This method is the wrapper version of `_.reverse`. **Note:** This method mutates the wrapped array.
Since:
  • 0.1.0
Source:
Example
var array = [1, 2, 3];

_(array).reverse().value()
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) round

Computes `number` rounded to `precision`.
Since:
  • 3.10.0
Source:
Example
_.round(4.006);
// => 4

_.round(4.006, 2);
// => 4.01

_.round(4060, -2);
// => 4100

(static) round

Computes `number` rounded to `precision`.
Since:
  • 3.10.0
Source:
Example
_.round(4.006);
// => 4

_.round(4.006, 2);
// => 4.01

_.round(4060, -2);
// => 4100

(static) snakeCase

Converts `string` to [snake case](https://en.wikipedia.org/wiki/Snake_case).
Since:
  • 3.0.0
Source:
Example
_.snakeCase('Foo Bar');
// => 'foo_bar'

_.snakeCase('fooBar');
// => 'foo_bar'

_.snakeCase('--FOO-BAR--');
// => 'foo_bar'

(static) snakeCase

Converts `string` to [snake case](https://en.wikipedia.org/wiki/Snake_case).
Since:
  • 3.0.0
Source:
Example
_.snakeCase('Foo Bar');
// => 'foo_bar'

_.snakeCase('fooBar');
// => 'foo_bar'

_.snakeCase('--FOO-BAR--');
// => 'foo_bar'

(static) sortBy

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) sortBy

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) startCase

Converts `string` to [start case](https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage).
Since:
  • 3.1.0
Source:
Example
_.startCase('--foo-bar--');
// => 'Foo Bar'

_.startCase('fooBar');
// => 'Foo Bar'

_.startCase('__FOO_BAR__');
// => 'FOO BAR'

(static) startCase

Converts `string` to [start case](https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage).
Since:
  • 3.1.0
Source:
Example
_.startCase('--foo-bar--');
// => 'Foo Bar'

_.startCase('fooBar');
// => 'Foo Bar'

_.startCase('__FOO_BAR__');
// => 'FOO BAR'

(static) subtract

Subtract two numbers.
Since:
  • 4.0.0
Source:
Example
_.subtract(6, 4);
// => 2

(static) subtract

Subtract two numbers.
Since:
  • 4.0.0
Source:
Example
_.subtract(6, 4);
// => 2

(static) templateSettings :Object

By default, the template delimiters used by lodash are like those in embedded Ruby (ERB) as well as ES2015 template strings. Change the following template settings to use alternative delimiters.
Type:
  • Object
Source:

(static) toInteger

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Since:
  • 4.0.0
Source:
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toNumber

Converts `value` to a number.
Since:
  • 4.0.0
Source:
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) union

Creates an array of unique values, in order, from all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons.
Since:
  • 0.1.0
Source:
Example
_.union([2], [1, 2]);
// => [2, 1]

(static) union

Creates an array of unique values, in order, from all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons.
Since:
  • 0.1.0
Source:
Example
_.union([2], [1, 2]);
// => [2, 1]

(static) unionBy

This method is like `_.union` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which uniqueness is computed. Result values are chosen from the first array in which the value occurs. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) unionBy

This method is like `_.union` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which uniqueness is computed. Result values are chosen from the first array in which the value occurs. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) unionWith

This method is like `_.union` except that it accepts `comparator` which is invoked to compare elements of `arrays`. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.unionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) unionWith

This method is like `_.union` except that it accepts `comparator` which is invoked to compare elements of `arrays`. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.unionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) upperCase

Converts `string`, as space separated words, to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperCase('--foo-bar');
// => 'FOO BAR'

_.upperCase('fooBar');
// => 'FOO BAR'

_.upperCase('__foo_bar__');
// => 'FOO BAR'

(static) upperCase

Converts `string`, as space separated words, to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperCase('--foo-bar');
// => 'FOO BAR'

_.upperCase('fooBar');
// => 'FOO BAR'

_.upperCase('__foo_bar__');
// => 'FOO BAR'

(static) upperFirst

Converts the first character of `string` to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

(static) upperFirst

Converts the first character of `string` to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

(static) without

Creates an array excluding all given values using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.pull`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2);
// => [3]

(static) without

Creates an array excluding all given values using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.pull`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2);
// => [3]

(static) xor

Creates an array of unique values that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference) of the given arrays. The order of result values is determined by the order they occur in the arrays.
Since:
  • 2.4.0
Source:
See:
  • _.difference, _.without
Example
_.xor([2, 1], [2, 3]);
// => [1, 3]

(static) xor

Creates an array of unique values that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference) of the given arrays. The order of result values is determined by the order they occur in the arrays.
Since:
  • 2.4.0
Source:
See:
  • _.difference, _.without
Example
_.xor([2, 1], [2, 3]);
// => [1, 3]

(static) xorBy

This method is like `_.xor` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which by which they're compared. The order of result values is determined by the order they occur in the arrays. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2, 3.4]

// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) xorBy

This method is like `_.xor` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which by which they're compared. The order of result values is determined by the order they occur in the arrays. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2, 3.4]

// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) xorWith

This method is like `_.xor` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order of result values is determined by the order they occur in the arrays. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.xorWith(objects, others, _.isEqual);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) xorWith

This method is like `_.xor` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order of result values is determined by the order they occur in the arrays. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.xorWith(objects, others, _.isEqual);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
Since:
  • 0.1.0
Source:
Example
_.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

(static) zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
Since:
  • 0.1.0
Source:
Example
_.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

(static) zipWith

This method is like `_.zip` except that it accepts `iteratee` to specify how grouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Since:
  • 3.8.0
Source:
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// => [111, 222]

(static) zipWith

This method is like `_.zip` except that it accepts `iteratee` to specify how grouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Since:
  • 3.8.0
Source:
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// => [111, 222]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

Methods

(static) after(n, func) → {function}

The opposite of `_.before`; this method creates a function that invokes `func` once it's called `n` or more times.
Parameters:
Name Type Description
n number The number of calls before `func` is invoked.
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
  console.log('done saving!');
});

_.forEach(saves, function(type) {
  asyncSave({ 'type': type, 'complete': done });
});
// => Logs 'done saving!' after the two async saves have completed.

(static) after(n, func) → {function}

The opposite of `_.before`; this method creates a function that invokes `func` once it's called `n` or more times.
Parameters:
Name Type Description
n number The number of calls before `func` is invoked.
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
  console.log('done saving!');
});

_.forEach(saves, function(type) {
  asyncSave({ 'type': type, 'complete': done });
});
// => Logs 'done saving!' after the two async saves have completed.

(static) ary(func, nopt) → {function}

Creates a function that invokes `func`, with up to `n` arguments, ignoring any additional arguments.
Parameters:
Name Type Attributes Default Description
func function The function to cap arguments for.
n number <optional>
func.length The arity cap.
Since:
  • 3.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// => [6, 8, 10]

(static) ary(func, nopt) → {function}

Creates a function that invokes `func`, with up to `n` arguments, ignoring any additional arguments.
Parameters:
Name Type Attributes Default Description
func function The function to cap arguments for.
n number <optional>
func.length The arity cap.
Since:
  • 3.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// => [6, 8, 10]

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) capitalize(stringopt) → {string}

Converts the first character of `string` to upper case and the remaining to lower case.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to capitalize.
Since:
  • 3.0.0
Source:
Returns:
Returns the capitalized string.
Type
string
Example
_.capitalize('FRED');
// => 'Fred'

(static) capitalize(stringopt) → {string}

Converts the first character of `string` to upper case and the remaining to lower case.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to capitalize.
Since:
  • 3.0.0
Source:
Returns:
Returns the capitalized string.
Type
string
Example
_.capitalize('FRED');
// => 'Fred'

(static) castArray(value) → {Array}

Casts `value` as an array if it's not one.
Parameters:
Name Type Description
value * The value to inspect.
Since:
  • 4.4.0
Source:
Returns:
Returns the cast array.
Type
Array
Example
_.castArray(1);
// => [1]

_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]

_.castArray('abc');
// => ['abc']

_.castArray(null);
// => [null]

_.castArray(undefined);
// => [undefined]

_.castArray();
// => []

var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

(static) castArray(value) → {Array}

Casts `value` as an array if it's not one.
Parameters:
Name Type Description
value * The value to inspect.
Since:
  • 4.4.0
Source:
Returns:
Returns the cast array.
Type
Array
Example
_.castArray(1);
// => [1]

_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]

_.castArray('abc');
// => ['abc']

_.castArray(null);
// => [null]

_.castArray(undefined);
// => [undefined]

_.castArray();
// => []

var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chunk(array, sizeopt) → {Array}

Creates an array of elements split into groups the length of `size`. If `array` can't be split evenly, the final chunk will be the remaining elements.
Parameters:
Name Type Attributes Default Description
array Array The array to process.
size number <optional>
1 The length of each chunk
Since:
  • 3.0.0
Source:
Returns:
Returns the new array of chunks.
Type
Array
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]

(static) chunk(array, sizeopt) → {Array}

Creates an array of elements split into groups the length of `size`. If `array` can't be split evenly, the final chunk will be the remaining elements.
Parameters:
Name Type Attributes Default Description
array Array The array to process.
size number <optional>
1 The length of each chunk
Since:
  • 3.0.0
Source:
Returns:
Returns the new array of chunks.
Type
Array
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]

(static) clamp(number, loweropt, upper) → {number}

Clamps `number` within the inclusive `lower` and `upper` bounds.
Parameters:
Name Type Attributes Description
number number The number to clamp.
lower number <optional>
The lower bound.
upper number The upper bound.
Since:
  • 4.0.0
Source:
Returns:
Returns the clamped number.
Type
number
Example
_.clamp(-10, -5, 5);
// => -5

_.clamp(10, -5, 5);
// => 5

(static) clamp(number, loweropt, upper) → {number}

Clamps `number` within the inclusive `lower` and `upper` bounds.
Parameters:
Name Type Attributes Description
number number The number to clamp.
lower number <optional>
The lower bound.
upper number The upper bound.
Since:
  • 4.0.0
Source:
Returns:
Returns the clamped number.
Type
number
Example
_.clamp(-10, -5, 5);
// => -5

_.clamp(10, -5, 5);
// => 5

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) cloneDeep(value) → {*}

This method is like `_.clone` except that it recursively clones `value`.
Parameters:
Name Type Description
value * The value to recursively clone.
Since:
  • 1.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false

(static) cloneDeep(value) → {*}

This method is like `_.clone` except that it recursively clones `value`.
Parameters:
Name Type Description
value * The value to recursively clone.
Since:
  • 1.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false

(static) cloneDeepWith(value, customizeropt) → {*}

This method is like `_.cloneWith` except that it recursively clones `value`.
Parameters:
Name Type Attributes Description
value * The value to recursively clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(true);
  }
}

var el = _.cloneDeepWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20

(static) cloneDeepWith(value, customizeropt) → {*}

This method is like `_.cloneWith` except that it recursively clones `value`.
Parameters:
Name Type Attributes Description
value * The value to recursively clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(true);
  }
}

var el = _.cloneDeepWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20

(static) cloneWith(value, customizeropt) → {*}

This method is like `_.clone` except that it accepts `customizer` which is invoked to produce the cloned value. If `customizer` returns `undefined`, cloning is handled by the method instead. The `customizer` is invoked with up to four arguments; (value [, index|key, object, stack]).
Parameters:
Name Type Attributes Description
value * The value to clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(false);
  }
}

var el = _.cloneWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0

(static) cloneWith(value, customizeropt) → {*}

This method is like `_.clone` except that it accepts `customizer` which is invoked to produce the cloned value. If `customizer` returns `undefined`, cloning is handled by the method instead. The `customizer` is invoked with up to four arguments; (value [, index|key, object, stack]).
Parameters:
Name Type Attributes Description
value * The value to clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(false);
  }
}

var el = _.cloneWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) cond(pairs) → {function}

Creates a function that iterates over `pairs` and invokes the corresponding function of the first predicate to return truthy. The predicate-function pairs are invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
pairs Array The predicate-function pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new composite function.
Type
function
Example
var func = _.cond([
  [_.matches({ 'a': 1 }),           _.constant('matches A')],
  [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
  [_.stubTrue,                      _.constant('no match')]
]);

func({ 'a': 1, 'b': 2 });
// => 'matches A'

func({ 'a': 0, 'b': 1 });
// => 'matches B'

func({ 'a': '1', 'b': '2' });
// => 'no match'

(static) cond(pairs) → {function}

Creates a function that iterates over `pairs` and invokes the corresponding function of the first predicate to return truthy. The predicate-function pairs are invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
pairs Array The predicate-function pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new composite function.
Type
function
Example
var func = _.cond([
  [_.matches({ 'a': 1 }),           _.constant('matches A')],
  [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
  [_.stubTrue,                      _.constant('no match')]
]);

func({ 'a': 1, 'b': 2 });
// => 'matches A'

func({ 'a': 0, 'b': 1 });
// => 'matches B'

func({ 'a': '1', 'b': '2' });
// => 'no match'

(static) conforms(source) → {function}

Creates a function that invokes the predicate properties of `source` with the corresponding property values of a given object, returning `true` if all predicates return truthy, else `false`. **Note:** The created function is equivalent to `_.conformsTo` with `source` partially applied.
Parameters:
Name Type Description
source Object The object of property predicates to conform to.
Since:
  • 4.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 2, 'b': 1 },
  { 'a': 1, 'b': 2 }
];

_.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } }));
// => [{ 'a': 1, 'b': 2 }]

(static) conforms(source) → {function}

Creates a function that invokes the predicate properties of `source` with the corresponding property values of a given object, returning `true` if all predicates return truthy, else `false`. **Note:** The created function is equivalent to `_.conformsTo` with `source` partially applied.
Parameters:
Name Type Description
source Object The object of property predicates to conform to.
Since:
  • 4.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 2, 'b': 1 },
  { 'a': 1, 'b': 2 }
];

_.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } }));
// => [{ 'a': 1, 'b': 2 }]

(static) conformsTo(object, source) → {boolean}

Checks if `object` conforms to `source` by invoking the predicate properties of `source` with the corresponding property values of `object`. **Note:** This method is equivalent to `_.conforms` when `source` is partially applied.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property predicates to conform to.
Since:
  • 4.14.0
Source:
Returns:
Returns `true` if `object` conforms, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.conformsTo(object, { 'b': function(n) { return n > 1; } });
// => true

_.conformsTo(object, { 'b': function(n) { return n > 2; } });
// => false

(static) conformsTo(object, source) → {boolean}

Checks if `object` conforms to `source` by invoking the predicate properties of `source` with the corresponding property values of `object`. **Note:** This method is equivalent to `_.conforms` when `source` is partially applied.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property predicates to conform to.
Since:
  • 4.14.0
Source:
Returns:
Returns `true` if `object` conforms, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.conformsTo(object, { 'b': function(n) { return n > 1; } });
// => true

_.conformsTo(object, { 'b': function(n) { return n > 2; } });
// => false

(static) constant(value) → {function}

Creates a function that returns `value`.
Parameters:
Name Type Description
value * The value to return from the new function.
Since:
  • 2.4.0
Source:
Returns:
Returns the new constant function.
Type
function
Example
var objects = _.times(2, _.constant({ 'a': 1 }));

console.log(objects);
// => [{ 'a': 1 }, { 'a': 1 }]

console.log(objects[0] === objects[1]);
// => true

(static) constant(value) → {function}

Creates a function that returns `value`.
Parameters:
Name Type Description
value * The value to return from the new function.
Since:
  • 2.4.0
Source:
Returns:
Returns the new constant function.
Type
function
Example
var objects = _.times(2, _.constant({ 'a': 1 }));

console.log(objects);
// => [{ 'a': 1 }, { 'a': 1 }]

console.log(objects[0] === objects[1]);
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) curry(func, arityopt) → {function}

Creates a function that accepts arguments of `func` and either invokes `func` returning its result, if at least `arity` number of arguments have been provided, or returns a function that accepts the remaining `func` arguments, and so on. The arity of `func` may be specified if `func.length` is not sufficient. The `_.curry.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 2.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curry(abc);

curried(1)(2)(3);
// => [1, 2, 3]

curried(1, 2)(3);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]

(static) curry(func, arityopt) → {function}

Creates a function that accepts arguments of `func` and either invokes `func` returning its result, if at least `arity` number of arguments have been provided, or returns a function that accepts the remaining `func` arguments, and so on. The arity of `func` may be specified if `func.length` is not sufficient. The `_.curry.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 2.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curry(abc);

curried(1)(2)(3);
// => [1, 2, 3]

curried(1, 2)(3);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]

(static) curryRight(func, arityopt) → {function}

This method is like `_.curry` except that arguments are applied to `func` in the manner of `_.partialRight` instead of `_.partial`. The `_.curryRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 3.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curryRight(abc);

curried(3)(2)(1);
// => [1, 2, 3]

curried(2, 3)(1);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]

(static) curryRight(func, arityopt) → {function}

This method is like `_.curry` except that arguments are applied to `func` in the manner of `_.partialRight` instead of `_.partial`. The `_.curryRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 3.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curryRight(abc);

curried(3)(2)(1);
// => [1, 2, 3]

curried(2, 3)(1);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]

(static) debounce(func, waitopt, optionsopt) → {function}

Creates a debounced function that delays invoking `func` until after `wait` milliseconds have elapsed since the last time the debounced function was invoked. The debounced function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the debounced function. Subsequent calls to the debounced function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the debounced function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.debounce` and `_.throttle`.
Parameters:
Name Type Attributes Default Description
func function The function to debounce.
wait number <optional>
0 The number of milliseconds to delay.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait number <optional>
The maximum time `func` is allowed to be delayed before it's invoked.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new debounced function.
Type
function
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));

// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));

// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);

// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);

(static) debounce(func, waitopt, optionsopt) → {function}

Creates a debounced function that delays invoking `func` until after `wait` milliseconds have elapsed since the last time the debounced function was invoked. The debounced function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the debounced function. Subsequent calls to the debounced function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the debounced function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.debounce` and `_.throttle`.
Parameters:
Name Type Attributes Default Description
func function The function to debounce.
wait number <optional>
0 The number of milliseconds to delay.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait number <optional>
The maximum time `func` is allowed to be delayed before it's invoked.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new debounced function.
Type
function
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));

// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));

// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);

// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);

(static) deburr(stringopt) → {string}

Deburrs `string` by converting [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table) and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A) letters to basic Latin letters and removing [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to deburr.
Since:
  • 3.0.0
Source:
Returns:
Returns the deburred string.
Type
string
Example
_.deburr('déjà vu');
// => 'deja vu'

(static) deburr(stringopt) → {string}

Deburrs `string` by converting [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table) and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A) letters to basic Latin letters and removing [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to deburr.
Since:
  • 3.0.0
Source:
Returns:
Returns the deburred string.
Type
string
Example
_.deburr('déjà vu');
// => 'deja vu'

(static) defaultTo(value, defaultValue) → {*}

Checks `value` to determine whether a default value should be returned in its place. The `defaultValue` is returned if `value` is `NaN`, `null`, or `undefined`.
Parameters:
Name Type Description
value * The value to check.
defaultValue * The default value.
Since:
  • 4.14.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
_.defaultTo(1, 10);
// => 1

_.defaultTo(undefined, 10);
// => 10

(static) defaultTo(value, defaultValue) → {*}

Checks `value` to determine whether a default value should be returned in its place. The `defaultValue` is returned if `value` is `NaN`, `null`, or `undefined`.
Parameters:
Name Type Description
value * The value to check.
defaultValue * The default value.
Since:
  • 4.14.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
_.defaultTo(1, 10);
// => 1

_.defaultTo(undefined, 10);
// => 10

(static) drop(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 0.5.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

_.drop([1, 2, 3], 5);
// => []

_.drop([1, 2, 3], 0);
// => [1, 2, 3]

(static) drop(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 0.5.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

_.drop([1, 2, 3], 5);
// => []

_.drop([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

_.dropRight([1, 2, 3], 5);
// => []

_.dropRight([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

_.dropRight([1, 2, 3], 5);
// => []

_.dropRight([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the end. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.dropRightWhile(users, function(o) { return !o.active; });
// => objects for ['barney']

// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['barney', 'fred']

// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// => objects for ['barney']

// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the end. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.dropRightWhile(users, function(o) { return !o.active; });
// => objects for ['barney']

// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['barney', 'fred']

// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// => objects for ['barney']

// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the beginning. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.dropWhile(users, function(o) { return !o.active; });
// => objects for ['pebbles']

// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['fred', 'pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// => objects for ['pebbles']

// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the beginning. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.dropWhile(users, function(o) { return !o.active; });
// => objects for ['pebbles']

// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['fred', 'pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// => objects for ['pebbles']

// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) eachRight(collection, iterateeopt) → {Array|Object}

This method is like `_.forEach` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
  • _.forEach
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEachRight([1, 2], function(value) {
  console.log(value);
});
// => Logs `2` then `1`.

(static) eachRight(collection, iterateeopt) → {Array|Object}

This method is like `_.forEach` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
  • _.forEach
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEachRight([1, 2], function(value) {
  console.log(value);
});
// => Logs `2` then `1`.

(static) endsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` ends with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
string.length The position to search up to.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` ends with `target`, else `false`.
Type
boolean
Example
_.endsWith('abc', 'c');
// => true

_.endsWith('abc', 'b');
// => false

_.endsWith('abc', 'b', 2);
// => true

(static) endsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` ends with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
string.length The position to search up to.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` ends with `target`, else `false`.
Type
boolean
Example
_.endsWith('abc', 'c');
// => true

_.endsWith('abc', 'b');
// => false

_.endsWith('abc', 'b', 2);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escapeRegExp(stringopt) → {string}

Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+", "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 3.0.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'

(static) escapeRegExp(stringopt) → {string}

Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+", "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 3.0.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) fill(array, value, startopt, endopt) → {Array}

Fills elements of `array` with `value` from `start` up to, but not including, `end`. **Note:** This method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to fill.
value * The value to fill `array` with.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.2.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.fill(array, 'a');
console.log(array);
// => ['a', 'a', 'a']

_.fill(Array(3), 2);
// => [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3);
// => [4, '*', '*', 10]

(static) fill(array, value, startopt, endopt) → {Array}

Fills elements of `array` with `value` from `start` up to, but not including, `end`. **Note:** This method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to fill.
value * The value to fill `array` with.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.2.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.fill(array, 'a');
console.log(array);
// => ['a', 'a', 'a']

_.fill(Array(3), 2);
// => [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3);
// => [4, '*', '*', 10]

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findKey(object, predicateopt) → {string|undefined}

This method is like `_.find` except that it returns the key of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 1.1.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

(static) findKey(object, predicateopt) → {string|undefined}

This method is like `_.find` except that it returns the key of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 1.1.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

(static) findLastIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.findIndex` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 2.0.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// => 2

// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// => 0

// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// => 2

// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// => 0

(static) findLastIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.findIndex` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 2.0.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// => 2

// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// => 0

// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// => 2

// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// => 0

(static) findLastKey(object, predicateopt) → {string|undefined}

This method is like `_.findKey` except that it iterates over elements of a collection in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'

// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'

// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'

(static) findLastKey(object, predicateopt) → {string|undefined}

This method is like `_.findKey` except that it iterates over elements of a collection in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'

// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'

// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) flatMap(collection, iterateeopt) → {Array}

Creates a flattened array of values by running each element in `collection` thru `iteratee` and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [n, n];
}

_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMap(collection, iterateeopt) → {Array}

Creates a flattened array of values by running each element in `collection` thru `iteratee` and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [n, n];
}

_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDeep(collection, iterateeopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDeep([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDeep(collection, iterateeopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDeep([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDepth(collection, iterateeopt, depthopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results up to `depth` times.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDepth([1, 2], duplicate, 2);
// => [[1, 1], [2, 2]]

(static) flatMapDepth(collection, iterateeopt, depthopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results up to `depth` times.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDepth([1, 2], duplicate, 2);
// => [[1, 1], [2, 2]]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDepth(array, depthopt) → {Array}

Recursively flatten `array` up to `depth` times.
Parameters:
Name Type Attributes Default Description
array Array The array to flatten.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.4.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
var array = [1, [2, [3, [4]], 5]];

_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]

_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

(static) flattenDepth(array, depthopt) → {Array}

Recursively flatten `array` up to `depth` times.
Parameters:
Name Type Attributes Default Description
array Array The array to flatten.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.4.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
var array = [1, [2, [3, [4]], 5]];

_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]

_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

(static) flip(func) → {function}

Creates a function that invokes `func` with arguments reversed.
Parameters:
Name Type Description
func function The function to flip arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flipped function.
Type
function
Example
var flipped = _.flip(function() {
  return _.toArray(arguments);
});

flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']

(static) flip(func) → {function}

Creates a function that invokes `func` with arguments reversed.
Parameters:
Name Type Description
func function The function to flip arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flipped function.
Type
function
Example
var flipped = _.flip(function() {
  return _.toArray(arguments);
});

flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']

(static) forIn(object, iterateeopt) → {Object}

Iterates over own and inherited enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forIn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).

(static) forIn(object, iterateeopt) → {Object}

Iterates over own and inherited enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forIn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).

(static) forInRight(object, iterateeopt) → {Object}

This method is like `_.forIn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forInRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.

(static) forInRight(object, iterateeopt) → {Object}

This method is like `_.forIn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forInRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.

(static) forOwn(object, iterateeopt) → {Object}

Iterates over own enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) forOwn(object, iterateeopt) → {Object}

Iterates over own enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) forOwnRight(object, iterateeopt) → {Object}

This method is like `_.forOwn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwnRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.

(static) forOwnRight(object, iterateeopt) → {Object}

This method is like `_.forOwn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwnRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.

(static) fromPairs(pairs) → {Object}

The inverse of `_.toPairs`; this method returns an object composed from key-value `pairs`.
Parameters:
Name Type Description
pairs Array The key-value pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

(static) fromPairs(pairs) → {Object}

The inverse of `_.toPairs`; this method returns an object composed from key-value `pairs`.
Parameters:
Name Type Description
pairs Array The key-value pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

(static) functions(object) → {Array}

Creates an array of function property names from own enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functions(new Foo);
// => ['a', 'b']

(static) functions(object) → {Array}

Creates an array of function property names from own enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functions(new Foo);
// => ['a', 'b']

(static) functionsIn(object) → {Array}

Creates an array of function property names from own and inherited enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functionsIn(new Foo);
// => ['a', 'b', 'c']

(static) functionsIn(object) → {Array}

Creates an array of function property names from own and inherited enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functionsIn(new Foo);
// => ['a', 'b', 'c']

(static) get(object, path, defaultValueopt) → {*}

Gets the value at `path` of `object`. If the resolved value is `undefined`, the `defaultValue` is returned in its place.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to get.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 3.7.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.get(object, 'a[0].b.c');
// => 3

_.get(object, ['a', '0', 'b', 'c']);
// => 3

_.get(object, 'a.b.c', 'default');
// => 'default'

(static) get(object, path, defaultValueopt) → {*}

Gets the value at `path` of `object`. If the resolved value is `undefined`, the `defaultValue` is returned in its place.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to get.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 3.7.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.get(object, 'a[0].b.c');
// => 3

_.get(object, ['a', '0', 'b', 'c']);
// => 3

_.get(object, 'a.b.c', 'default');
// => 'default'

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) hasIn(object, path) → {boolean}

Checks if `path` is a direct or inherited property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) });

_.hasIn(object, 'a');
// => true

_.hasIn(object, 'a.b');
// => true

_.hasIn(object, ['a', 'b']);
// => true

_.hasIn(object, 'b');
// => false

(static) hasIn(object, path) → {boolean}

Checks if `path` is a direct or inherited property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) });

_.hasIn(object, 'a');
// => true

_.hasIn(object, 'a.b');
// => true

_.hasIn(object, ['a', 'b']);
// => true

_.hasIn(object, 'b');
// => false

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) inRange(number, startopt, end) → {boolean}

Checks if `n` is between `start` and up to, but not including, `end`. If `end` is not specified, it's set to `start` with `start` then set to `0`. If `start` is greater than `end` the params are swapped to support negative ranges.
Parameters:
Name Type Attributes Default Description
number number The number to check.
start number <optional>
0 The start of the range.
end number The end of the range.
Since:
  • 3.3.0
Source:
See:
  • _.range, _.rangeRight
Returns:
Returns `true` if `number` is in the range, else `false`.
Type
boolean
Example
_.inRange(3, 2, 4);
// => true

_.inRange(4, 8);
// => true

_.inRange(4, 2);
// => false

_.inRange(2, 2);
// => false

_.inRange(1.2, 2);
// => true

_.inRange(5.2, 4);
// => false

_.inRange(-3, -2, -6);
// => true

(static) inRange(number, startopt, end) → {boolean}

Checks if `n` is between `start` and up to, but not including, `end`. If `end` is not specified, it's set to `start` with `start` then set to `0`. If `start` is greater than `end` the params are swapped to support negative ranges.
Parameters:
Name Type Attributes Default Description
number number The number to check.
start number <optional>
0 The start of the range.
end number The end of the range.
Since:
  • 3.3.0
Source:
See:
  • _.range, _.rangeRight
Returns:
Returns `true` if `number` is in the range, else `false`.
Type
boolean
Example
_.inRange(3, 2, 4);
// => true

_.inRange(4, 8);
// => true

_.inRange(4, 2);
// => false

_.inRange(2, 2);
// => false

_.inRange(1.2, 2);
// => true

_.inRange(5.2, 4);
// => false

_.inRange(-3, -2, -6);
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) initial(array) → {Array}

Gets all but the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.initial([1, 2, 3]);
// => [1, 2]

(static) initial(array) → {Array}

Gets all but the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.initial([1, 2, 3]);
// => [1, 2]

(static) isArguments(value) → {boolean}

Checks if `value` is likely an `arguments` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an `arguments` object, else `false`.
Type
boolean
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isElement(value) → {boolean}

Checks if `value` is likely a DOM element.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a DOM element, else `false`.
Type
boolean
Example
_.isElement(document.body);
// => true

_.isElement('<body>');
// => false

(static) isElement(value) → {boolean}

Checks if `value` is likely a DOM element.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a DOM element, else `false`.
Type
boolean
Example
_.isElement(document.body);
// => true

_.isElement('<body>');
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqualWith(value, other, customizeropt) → {boolean}

This method is like `_.isEqual` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with up to six arguments: (objValue, othValue [, index|key, object, other, stack]).
Parameters:
Name Type Attributes Description
value * The value to compare.
other * The other value to compare.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, othValue) {
  if (isGreeting(objValue) && isGreeting(othValue)) {
    return true;
  }
}

var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];

_.isEqualWith(array, other, customizer);
// => true

(static) isEqualWith(value, other, customizeropt) → {boolean}

This method is like `_.isEqual` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with up to six arguments: (objValue, othValue [, index|key, object, other, stack]).
Parameters:
Name Type Attributes Description
value * The value to compare.
other * The other value to compare.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, othValue) {
  if (isGreeting(objValue) && isGreeting(othValue)) {
    return true;
  }
}

var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];

_.isEqualWith(array, other, customizer);
// => true

(static) isError(value) → {boolean}

Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, or `URIError` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is an error object, else `false`.
Type
boolean
Example
_.isError(new Error);
// => true

_.isError(Error);
// => false

(static) isError(value) → {boolean}

Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, or `URIError` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is an error object, else `false`.
Type
boolean
Example
_.isError(new Error);
// => true

_.isError(Error);
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isMatch(object, source) → {boolean}

Performs a partial deep comparison between `object` and `source` to determine if `object` contains equivalent property values. **Note:** This method is equivalent to `_.matches` when `source` is partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.isMatch(object, { 'b': 2 });
// => true

_.isMatch(object, { 'b': 1 });
// => false

(static) isMatch(object, source) → {boolean}

Performs a partial deep comparison between `object` and `source` to determine if `object` contains equivalent property values. **Note:** This method is equivalent to `_.matches` when `source` is partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.isMatch(object, { 'b': 2 });
// => true

_.isMatch(object, { 'b': 1 });
// => false

(static) isMatchWith(object, source, customizeropt) → {boolean}

This method is like `_.isMatch` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, index|key, object, source).
Parameters:
Name Type Attributes Description
object Object The object to inspect.
source Object The object of property values to match.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, srcValue) {
  if (isGreeting(objValue) && isGreeting(srcValue)) {
    return true;
  }
}

var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };

_.isMatchWith(object, source, customizer);
// => true

(static) isMatchWith(object, source, customizeropt) → {boolean}

This method is like `_.isMatch` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, index|key, object, source).
Parameters:
Name Type Attributes Description
object Object The object to inspect.
source Object The object of property values to match.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, srcValue) {
  if (isGreeting(objValue) && isGreeting(srcValue)) {
    return true;
  }
}

var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };

_.isMatchWith(object, source, customizer);
// => true

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNative(value) → {boolean}

Checks if `value` is a pristine native function. **Note:** This method can't reliably detect native functions in the presence of the core-js package because core-js circumvents this kind of detection. Despite multiple requests, the core-js maintainer has made it clear: any attempt to fix the detection will be obstructed. As a result, we're left with little choice but to throw an error. Unfortunately, this also affects packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill), which rely on core-js.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is a native function, else `false`.
Type
boolean
Example
_.isNative(Array.prototype.push);
// => true

_.isNative(_);
// => false

(static) isNative(value) → {boolean}

Checks if `value` is a pristine native function. **Note:** This method can't reliably detect native functions in the presence of the core-js package because core-js circumvents this kind of detection. Despite multiple requests, the core-js maintainer has made it clear: any attempt to fix the detection will be obstructed. As a result, we're left with little choice but to throw an error. Unfortunately, this also affects packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill), which rely on core-js.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is a native function, else `false`.
Type
boolean
Example
_.isNative(Array.prototype.push);
// => true

_.isNative(_);
// => false

(static) isNil(value) → {boolean}

Checks if `value` is `null` or `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is nullish, else `false`.
Type
boolean
Example
_.isNil(null);
// => true

_.isNil(void 0);
// => true

_.isNil(NaN);
// => false

(static) isNil(value) → {boolean}

Checks if `value` is `null` or `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is nullish, else `false`.
Type
boolean
Example
_.isNil(null);
// => true

_.isNil(void 0);
// => true

_.isNil(NaN);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isSafeInteger(value) → {boolean}

Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754 double precision number which isn't the result of a rounded unsafe integer. **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a safe integer, else `false`.
Type
boolean
Example
_.isSafeInteger(3);
// => true

_.isSafeInteger(Number.MIN_VALUE);
// => false

_.isSafeInteger(Infinity);
// => false

_.isSafeInteger('3');
// => false

(static) isSafeInteger(value) → {boolean}

Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754 double precision number which isn't the result of a rounded unsafe integer. **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a safe integer, else `false`.
Type
boolean
Example
_.isSafeInteger(3);
// => true

_.isSafeInteger(Number.MIN_VALUE);
// => false

_.isSafeInteger(Infinity);
// => false

_.isSafeInteger('3');
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isWeakMap(value) → {boolean}

Checks if `value` is classified as a `WeakMap` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak map, else `false`.
Type
boolean
Example
_.isWeakMap(new WeakMap);
// => true

_.isWeakMap(new Map);
// => false

(static) isWeakMap(value) → {boolean}

Checks if `value` is classified as a `WeakMap` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak map, else `false`.
Type
boolean
Example
_.isWeakMap(new WeakMap);
// => true

_.isWeakMap(new Map);
// => false

(static) isWeakSet(value) → {boolean}

Checks if `value` is classified as a `WeakSet` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak set, else `false`.
Type
boolean
Example
_.isWeakSet(new WeakSet);
// => true

_.isWeakSet(new Set);
// => false

(static) isWeakSet(value) → {boolean}

Checks if `value` is classified as a `WeakSet` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak set, else `false`.
Type
boolean
Example
_.isWeakSet(new WeakSet);
// => true

_.isWeakSet(new Set);
// => false

(static) iteratee(funcopt) → {function}

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Parameters:
Name Type Attributes Default Description
func * <optional>
_.identity The value to convert to a callback.
Since:
  • 4.0.0
Source:
Returns:
Returns the callback.
Type
function
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) iteratee(funcopt) → {function}

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Parameters:
Name Type Attributes Default Description
func * <optional>
_.identity The value to convert to a callback.
Since:
  • 4.0.0
Source:
Returns:
Returns the callback.
Type
function
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) join(array, separatoropt) → {string}

Converts all elements in `array` into a string separated by `separator`.
Parameters:
Name Type Attributes Default Description
array Array The array to convert.
separator string <optional>
',' The element separator.
Since:
  • 4.0.0
Source:
Returns:
Returns the joined string.
Type
string
Example
_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'

(static) join(array, separatoropt) → {string}

Converts all elements in `array` into a string separated by `separator`.
Parameters:
Name Type Attributes Default Description
array Array The array to convert.
separator string <optional>
',' The element separator.
Since:
  • 4.0.0
Source:
Returns:
Returns the joined string.
Type
string
Example
_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keysIn(object) → {Array}

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) keysIn(object) → {Array}

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) lastIndexOf(array, value, fromIndexopt) → {number}

This method is like `_.indexOf` except that it iterates over elements of `array` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// => 3

// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// => 1

(static) lastIndexOf(array, value, fromIndexopt) → {number}

This method is like `_.indexOf` except that it iterates over elements of `array` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// => 3

// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// => 1

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) mapKeys(object, iterateeopt) → {Object}

The opposite of `_.mapValues`; this method creates an object with the same values as `object` and keys generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.8.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
  return key + value;
});
// => { 'a1': 1, 'b2': 2 }

(static) mapKeys(object, iterateeopt) → {Object}

The opposite of `_.mapValues`; this method creates an object with the same values as `object` and keys generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.8.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
  return key + value;
});
// => { 'a1': 1, 'b2': 2 }

(static) mapValues(object, iterateeopt) → {Object}

Creates an object with the same keys as `object` and values generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.4.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

(static) mapValues(object, iterateeopt) → {Object}

Creates an object with the same keys as `object` and values generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.4.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matchesProperty(path, srcValue) → {function}

Creates a function that performs a partial deep comparison between the value at `path` of a given object to `srcValue`, returning `true` if the object value is equivalent, else `false`. **Note:** Partial comparisons will match empty array and empty object `srcValue` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
path Array | string The path of the property to get.
srcValue * The value to match.
Since:
  • 3.2.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.find(objects, _.matchesProperty('a', 4));
// => { 'a': 4, 'b': 5, 'c': 6 }

// Checking for several possible values
_.filter(objects, _.overSome([_.matchesProperty('a', 1), _.matchesProperty('a', 4)]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matchesProperty(path, srcValue) → {function}

Creates a function that performs a partial deep comparison between the value at `path` of a given object to `srcValue`, returning `true` if the object value is equivalent, else `false`. **Note:** Partial comparisons will match empty array and empty object `srcValue` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
path Array | string The path of the property to get.
srcValue * The value to match.
Since:
  • 3.2.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.find(objects, _.matchesProperty('a', 4));
// => { 'a': 4, 'b': 5, 'c': 6 }

// Checking for several possible values
_.filter(objects, _.overSome([_.matchesProperty('a', 1), _.matchesProperty('a', 4)]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) maxBy(array, iterateeopt) → {*}

This method is like `_.max` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.maxBy(objects, function(o) { return o.n; });
// => { 'n': 2 }

// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// => { 'n': 2 }

(static) maxBy(array, iterateeopt) → {*}

This method is like `_.max` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.maxBy(objects, function(o) { return o.n; });
// => { 'n': 2 }

// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// => { 'n': 2 }

(static) mean(array) → {number}

Computes the mean of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 4.0.0
Source:
Returns:
Returns the mean.
Type
number
Example
_.mean([4, 2, 8, 6]);
// => 5

(static) mean(array) → {number}

Computes the mean of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 4.0.0
Source:
Returns:
Returns the mean.
Type
number
Example
_.mean([4, 2, 8, 6]);
// => 5

(static) meanBy(array, iterateeopt) → {number}

This method is like `_.mean` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be averaged. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.7.0
Source:
Returns:
Returns the mean.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.meanBy(objects, function(o) { return o.n; });
// => 5

// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// => 5

(static) meanBy(array, iterateeopt) → {number}

This method is like `_.mean` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be averaged. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.7.0
Source:
Returns:
Returns the mean.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.meanBy(objects, function(o) { return o.n; });
// => 5

// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// => 5

(static) memoize(func, resolveropt) → {function}

Creates a function that memoizes the result of `func`. If `resolver` is provided, it determines the cache key for storing the result based on the arguments provided to the memoized function. By default, the first argument provided to the memoized function is used as the map cache key. The `func` is invoked with the `this` binding of the memoized function. **Note:** The cache is exposed as the `cache` property on the memoized function. Its creation may be customized by replacing the `_.memoize.Cache` constructor with one whose instances implement the [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) method interface of `clear`, `delete`, `get`, `has`, and `set`.
Parameters:
Name Type Attributes Description
func function The function to have its output memoized.
resolver function <optional>
The function to resolve the cache key.
Since:
  • 0.1.0
Source:
Returns:
Returns the new memoized function.
Type
function
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };

var values = _.memoize(_.values);
values(object);
// => [1, 2]

values(other);
// => [3, 4]

object.a = 2;
values(object);
// => [1, 2]

// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']

// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;

(static) memoize(func, resolveropt) → {function}

Creates a function that memoizes the result of `func`. If `resolver` is provided, it determines the cache key for storing the result based on the arguments provided to the memoized function. By default, the first argument provided to the memoized function is used as the map cache key. The `func` is invoked with the `this` binding of the memoized function. **Note:** The cache is exposed as the `cache` property on the memoized function. Its creation may be customized by replacing the `_.memoize.Cache` constructor with one whose instances implement the [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) method interface of `clear`, `delete`, `get`, `has`, and `set`.
Parameters:
Name Type Attributes Description
func function The function to have its output memoized.
resolver function <optional>
The function to resolve the cache key.
Since:
  • 0.1.0
Source:
Returns:
Returns the new memoized function.
Type
function
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };

var values = _.memoize(_.values);
values(object);
// => [1, 2]

values(other);
// => [3, 4]

object.a = 2;
values(object);
// => [1, 2]

// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']

// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) minBy(array, iterateeopt) → {*}

This method is like `_.min` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }

// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

(static) minBy(array, iterateeopt) → {*}

This method is like `_.min` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }

// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) noConflict() → {function}

Reverts the `_` variable to its previous value and returns a reference to the `lodash` function.
Since:
  • 0.1.0
Source:
Returns:
Returns the `lodash` function.
Type
function
Example
var lodash = _.noConflict();

(static) noConflict() → {function}

Reverts the `_` variable to its previous value and returns a reference to the `lodash` function.
Since:
  • 0.1.0
Source:
Returns:
Returns the `lodash` function.
Type
function
Example
var lodash = _.noConflict();

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) now() → {number}

Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
Since:
  • 2.4.0
Source:
Returns:
Returns the timestamp.
Type
number
Example
_.defer(function(stamp) {
  console.log(_.now() - stamp);
}, _.now());
// => Logs the number of milliseconds it took for the deferred invocation.

(static) nth(array, nopt) → {*}

Gets the element at index `n` of `array`. If `n` is negative, the nth element from the end is returned.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
0 The index of the element to return.
Since:
  • 4.11.0
Source:
Returns:
Returns the nth element of `array`.
Type
*
Example
var array = ['a', 'b', 'c', 'd'];

_.nth(array, 1);
// => 'b'

_.nth(array, -2);
// => 'c';

(static) nth(array, nopt) → {*}

Gets the element at index `n` of `array`. If `n` is negative, the nth element from the end is returned.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
0 The index of the element to return.
Since:
  • 4.11.0
Source:
Returns:
Returns the nth element of `array`.
Type
*
Example
var array = ['a', 'b', 'c', 'd'];

_.nth(array, 1);
// => 'b'

_.nth(array, -2);
// => 'c';

(static) nthArg(nopt) → {function}

Creates a function that gets the argument at index `n`. If `n` is negative, the nth argument from the end is returned.
Parameters:
Name Type Attributes Default Description
n number <optional>
0 The index of the argument to return.
Since:
  • 4.0.0
Source:
Returns:
Returns the new pass-thru function.
Type
function
Example
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// => 'b'

var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// => 'c'

(static) nthArg(nopt) → {function}

Creates a function that gets the argument at index `n`. If `n` is negative, the nth argument from the end is returned.
Parameters:
Name Type Attributes Default Description
n number <optional>
0 The index of the argument to return.
Since:
  • 4.0.0
Source:
Returns:
Returns the new pass-thru function.
Type
function
Example
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// => 'b'

var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// => 'c'

(static) omitBy(object, predicateopt) → {Object}

The opposite of `_.pickBy`; this method creates an object composed of the own and inherited enumerable string keyed properties of `object` that `predicate` doesn't return truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omitBy(object, _.isNumber);
// => { 'b': '2' }

(static) omitBy(object, predicateopt) → {Object}

The opposite of `_.pickBy`; this method creates an object composed of the own and inherited enumerable string keyed properties of `object` that `predicate` doesn't return truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omitBy(object, _.isNumber);
// => { 'b': '2' }

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) orderBy(collection, iterateesopt, ordersopt) → {Array}

This method is like `_.sortBy` except that it allows specifying the sort orders of the iteratees to sort by. If `orders` is unspecified, all values are sorted in ascending order. Otherwise, specify an order of "desc" for descending or "asc" for ascending sort order of corresponding values.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees Array:.<Array:> | Array:.<function()> | Array:.<Object:> | Array:.<string:> <optional>
[_.identity] The iteratees to sort by.
orders Array:.<string:> <optional>
The sort orders of `iteratees`.
Since:
  • 4.0.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 34 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 36 }
];

// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

(static) orderBy(collection, iterateesopt, ordersopt) → {Array}

This method is like `_.sortBy` except that it allows specifying the sort orders of the iteratees to sort by. If `orders` is unspecified, all values are sorted in ascending order. Otherwise, specify an order of "desc" for descending or "asc" for ascending sort order of corresponding values.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees Array:.<Array:> | Array:.<function()> | Array:.<Object:> | Array:.<string:> <optional>
[_.identity] The iteratees to sort by.
orders Array:.<string:> <optional>
The sort orders of `iteratees`.
Since:
  • 4.0.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 34 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 36 }
];

// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

(static) pad(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left and right sides if it's shorter than `length`. Padding characters are truncated if they can't be evenly divided by `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 3.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.pad('abc', 8);
// => '  abc   '

_.pad('abc', 8, '_-');
// => '_-abc_-_'

_.pad('abc', 3);
// => 'abc'

(static) pad(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left and right sides if it's shorter than `length`. Padding characters are truncated if they can't be evenly divided by `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 3.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.pad('abc', 8);
// => '  abc   '

_.pad('abc', 8, '_-');
// => '_-abc_-_'

_.pad('abc', 3);
// => 'abc'

(static) padEnd(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the right side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padEnd('abc', 6);
// => 'abc   '

_.padEnd('abc', 6, '_-');
// => 'abc_-_'

_.padEnd('abc', 3);
// => 'abc'

(static) padEnd(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the right side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padEnd('abc', 6);
// => 'abc   '

_.padEnd('abc', 6, '_-');
// => 'abc_-_'

_.padEnd('abc', 3);
// => 'abc'

(static) padStart(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padStart('abc', 6);
// => '   abc'

_.padStart('abc', 6, '_-');
// => '_-_abc'

_.padStart('abc', 3);
// => 'abc'

(static) padStart(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padStart('abc', 6);
// => '   abc'

_.padStart('abc', 6, '_-');
// => '_-_abc'

_.padStart('abc', 3);
// => 'abc'

(static) parseInt(string, radixopt) → {number}

Converts `string` to an integer of the specified radix. If `radix` is `undefined` or `0`, a `radix` of `10` is used unless `value` is a hexadecimal, in which case a `radix` of `16` is used. **Note:** This method aligns with the [ES5 implementation](https://es5.github.io/#x15.1.2.2) of `parseInt`.
Parameters:
Name Type Attributes Default Description
string string The string to convert.
radix number <optional>
10 The radix to interpret `value` by.
Since:
  • 1.1.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.parseInt('08');
// => 8

_.map(['6', '08', '10'], _.parseInt);
// => [6, 8, 10]

(static) parseInt(string, radixopt) → {number}

Converts `string` to an integer of the specified radix. If `radix` is `undefined` or `0`, a `radix` of `10` is used unless `value` is a hexadecimal, in which case a `radix` of `16` is used. **Note:** This method aligns with the [ES5 implementation](https://es5.github.io/#x15.1.2.2) of `parseInt`.
Parameters:
Name Type Attributes Default Description
string string The string to convert.
radix number <optional>
10 The radix to interpret `value` by.
Since:
  • 1.1.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.parseInt('08');
// => 8

_.map(['6', '08', '10'], _.parseInt);
// => [6, 8, 10]

(static) pickBy(object, predicateopt) → {Object}

Creates an object composed of the `object` properties `predicate` returns truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

(static) pickBy(object, predicateopt) → {Object}

Creates an object composed of the `object` properties `predicate` returns truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

(static) property(path) → {function}

Creates a function that returns the value at `path` of a given object.
Parameters:
Name Type Description
path Array | string The path of the property to get.
Since:
  • 2.4.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];

_.map(objects, _.property('a.b'));
// => [2, 1]

_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// => [1, 2]

(static) property(path) → {function}

Creates a function that returns the value at `path` of a given object.
Parameters:
Name Type Description
path Array | string The path of the property to get.
Since:
  • 2.4.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];

_.map(objects, _.property('a.b'));
// => [2, 1]

_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// => [1, 2]

(static) propertyOf(object) → {function}

The opposite of `_.property`; this method creates a function that returns the value at a given path of `object`.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var array = [0, 1, 2],
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// => [2, 0]

(static) propertyOf(object) → {function}

The opposite of `_.property`; this method creates a function that returns the value at a given path of `object`.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var array = [0, 1, 2],
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// => [2, 0]

(static) pullAll(array, values) → {Array}

This method is like `_.pull` except that it accepts an array of values to remove. **Note:** Unlike `_.difference`, this method mutates `array`.
Parameters:
Name Type Description
array Array The array to modify.
values Array The values to remove.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pullAll(array, ['a', 'c']);
console.log(array);
// => ['b', 'b']

(static) pullAll(array, values) → {Array}

This method is like `_.pull` except that it accepts an array of values to remove. **Note:** Unlike `_.difference`, this method mutates `array`.
Parameters:
Name Type Description
array Array The array to modify.
values Array The values to remove.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pullAll(array, ['a', 'c']);
console.log(array);
// => ['b', 'b']

(static) pullAllBy(array, values, iterateeopt) → {Array}

This method is like `_.pullAll` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.differenceBy`, this method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
values Array The values to remove.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];

_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// => [{ 'x': 2 }]

(static) pullAllBy(array, values, iterateeopt) → {Array}

This method is like `_.pullAll` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.differenceBy`, this method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
values Array The values to remove.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];

_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// => [{ 'x': 2 }]

(static) pullAllWith(array, values, comparatoropt) → {Array}

This method is like `_.pullAll` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.differenceWith`, this method mutates `array`.
Parameters:
Name Type Attributes Description
array Array The array to modify.
values Array The values to remove.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.6.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];

_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]

(static) pullAllWith(array, values, comparatoropt) → {Array}

This method is like `_.pullAll` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.differenceWith`, this method mutates `array`.
Parameters:
Name Type Attributes Description
array Array The array to modify.
values Array The values to remove.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.6.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];

_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]

(static) random(loweropt, upperopt, floatingopt) → {number}

Produces a random number between the inclusive `lower` and `upper` bounds. If only one argument is provided a number between `0` and the given number is returned. If `floating` is `true`, or either `lower` or `upper` are floats, a floating-point number is returned instead of an integer. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Parameters:
Name Type Attributes Default Description
lower number <optional>
0 The lower bound.
upper number <optional>
1 The upper bound.
floating boolean <optional>
Specify returning a floating-point number.
Since:
  • 0.7.0
Source:
Returns:
Returns the random number.
Type
number
Example
_.random(0, 5);
// => an integer between 0 and 5

_.random(5);
// => also an integer between 0 and 5

_.random(5, true);
// => a floating-point number between 0 and 5

_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2

(static) random(loweropt, upperopt, floatingopt) → {number}

Produces a random number between the inclusive `lower` and `upper` bounds. If only one argument is provided a number between `0` and the given number is returned. If `floating` is `true`, or either `lower` or `upper` are floats, a floating-point number is returned instead of an integer. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Parameters:
Name Type Attributes Default Description
lower number <optional>
0 The lower bound.
upper number <optional>
1 The upper bound.
floating boolean <optional>
Specify returning a floating-point number.
Since:
  • 0.7.0
Source:
Returns:
Returns the random number.
Type
number
Example
_.random(0, 5);
// => an integer between 0 and 5

_.random(5);
// => also an integer between 0 and 5

_.random(5, true);
// => a floating-point number between 0 and 5

_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduceRight(collection, iterateeopt, accumulatoropt) → {*}

This method is like `_.reduce` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
var array = [[0, 1], [2, 3], [4, 5]];

_.reduceRight(array, function(flattened, other) {
  return flattened.concat(other);
}, []);
// => [4, 5, 2, 3, 0, 1]

(static) reduceRight(collection, iterateeopt, accumulatoropt) → {*}

This method is like `_.reduce` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
var array = [[0, 1], [2, 3], [4, 5]];

_.reduceRight(array, function(flattened, other) {
  return flattened.concat(other);
}, []);
// => [4, 5, 2, 3, 0, 1]

(static) reject(collection, predicateopt) → {Array}

The opposite of `_.filter`; this method returns the elements of `collection` that `predicate` does **not** return truthy for.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': true }
];

_.reject(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// => objects for ['barney']

(static) reject(collection, predicateopt) → {Array}

The opposite of `_.filter`; this method returns the elements of `collection` that `predicate` does **not** return truthy for.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': true }
];

_.reject(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// => objects for ['barney']

(static) remove(array, predicateopt) → {Array}

Removes all elements from `array` that `predicate` returns truthy for and returns an array of the removed elements. The predicate is invoked with three arguments: (value, index, array). **Note:** Unlike `_.filter`, this method mutates `array`. Use `_.pull` to pull elements from an array by value.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the new array of removed elements.
Type
Array
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

(static) remove(array, predicateopt) → {Array}

Removes all elements from `array` that `predicate` returns truthy for and returns an array of the removed elements. The predicate is invoked with three arguments: (value, index, array). **Note:** Unlike `_.filter`, this method mutates `array`. Use `_.pull` to pull elements from an array by value.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the new array of removed elements.
Type
Array
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

(static) repeat(stringopt, nopt) → {string}

Repeats the given string `n` times.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to repeat.
n number <optional>
1 The number of times to repeat the string.
Since:
  • 3.0.0
Source:
Returns:
Returns the repeated string.
Type
string
Example
_.repeat('*', 3);
// => '***'

_.repeat('abc', 2);
// => 'abcabc'

_.repeat('abc', 0);
// => ''

(static) repeat(stringopt, nopt) → {string}

Repeats the given string `n` times.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to repeat.
n number <optional>
1 The number of times to repeat the string.
Since:
  • 3.0.0
Source:
Returns:
Returns the repeated string.
Type
string
Example
_.repeat('*', 3);
// => '***'

_.repeat('abc', 2);
// => 'abcabc'

_.repeat('abc', 0);
// => ''

(static) replace(stringopt, pattern, replacement) → {string}

Replaces matches for `pattern` in `string` with `replacement`. **Note:** This method is based on [`String#replace`](https://mdn.io/String/replace).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to modify.
pattern RegExp | string The pattern to replace.
replacement function | string The match replacement.
Since:
  • 4.0.0
Source:
Returns:
Returns the modified string.
Type
string
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// => 'Hi Barney'

(static) replace(stringopt, pattern, replacement) → {string}

Replaces matches for `pattern` in `string` with `replacement`. **Note:** This method is based on [`String#replace`](https://mdn.io/String/replace).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to modify.
pattern RegExp | string The pattern to replace.
replacement function | string The match replacement.
Since:
  • 4.0.0
Source:
Returns:
Returns the modified string.
Type
string
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// => 'Hi Barney'

(static) rest(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the created function and arguments from `start` and beyond provided as an array. **Note:** This method is based on the [rest parameter](https://mdn.io/rest_parameters).
Parameters:
Name Type Attributes Default Description
func function The function to apply a rest parameter to.
start number <optional>
func.length-1 The start position of the rest parameter.
Since:
  • 4.0.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.rest(function(what, names) {
  return what + ' ' + _.initial(names).join(', ') +
    (_.size(names) > 1 ? ', & ' : '') + _.last(names);
});

say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'

(static) rest(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the created function and arguments from `start` and beyond provided as an array. **Note:** This method is based on the [rest parameter](https://mdn.io/rest_parameters).
Parameters:
Name Type Attributes Default Description
func function The function to apply a rest parameter to.
start number <optional>
func.length-1 The start position of the rest parameter.
Since:
  • 4.0.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.rest(function(what, names) {
  return what + ' ' + _.initial(names).join(', ') +
    (_.size(names) > 1 ? ', & ' : '') + _.last(names);
});

say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) reverse(array) → {Array}

Reverses `array` so that the first element becomes the last, the second element becomes the second to last, and so on. **Note:** This method mutates `array` and is based on [`Array#reverse`](https://mdn.io/Array/reverse).
Parameters:
Name Type Description
array Array The array to modify.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) reverse(array) → {Array}

Reverses `array` so that the first element becomes the last, the second element becomes the second to last, and so on. **Note:** This method mutates `array` and is based on [`Array#reverse`](https://mdn.io/Array/reverse).
Parameters:
Name Type Description
array Array The array to modify.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) runInContext(contextopt) → {function}

Create a new pristine `lodash` function using the `context` object.
Parameters:
Name Type Attributes Default Description
context Object <optional>
root The context object.
Since:
  • 1.1.0
Source:
Returns:
Returns a new `lodash` function.
Type
function
Example
_.mixin({ 'foo': _.constant('foo') });

var lodash = _.runInContext();
lodash.mixin({ 'bar': lodash.constant('bar') });

_.isFunction(_.foo);
// => true
_.isFunction(_.bar);
// => false

lodash.isFunction(lodash.foo);
// => false
lodash.isFunction(lodash.bar);
// => true

// Create a suped-up `defer` in Node.js.
var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;

(static) sample(collection) → {*}

Gets a random element from `collection`.
Parameters:
Name Type Description
collection Array | Object The collection to sample.
Since:
  • 2.0.0
Source:
Returns:
Returns the random element.
Type
*
Example
_.sample([1, 2, 3, 4]);
// => 2

(static) sample(collection) → {*}

Gets a random element from `collection`.
Parameters:
Name Type Description
collection Array | Object The collection to sample.
Since:
  • 2.0.0
Source:
Returns:
Returns the random element.
Type
*
Example
_.sample([1, 2, 3, 4]);
// => 2

(static) sampleSize(collection, nopt) → {Array}

Gets `n` random elements at unique keys from `collection` up to the size of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to sample.
n number <optional>
1 The number of elements to sample.
Since:
  • 4.0.0
Source:
Returns:
Returns the random elements.
Type
Array
Example
_.sampleSize([1, 2, 3], 2);
// => [3, 1]

_.sampleSize([1, 2, 3], 4);
// => [2, 3, 1]

(static) sampleSize(collection, nopt) → {Array}

Gets `n` random elements at unique keys from `collection` up to the size of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to sample.
n number <optional>
1 The number of elements to sample.
Since:
  • 4.0.0
Source:
Returns:
Returns the random elements.
Type
Array
Example
_.sampleSize([1, 2, 3], 2);
// => [3, 1]

_.sampleSize([1, 2, 3], 4);
// => [2, 3, 1]

(static) set(object, path, value) → {Object}

Sets the value at `path` of `object`. If a portion of `path` doesn't exist, it's created. Arrays are created for missing index properties while objects are created for all other missing properties. Use `_.setWith` to customize `path` creation. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
Since:
  • 3.7.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// => 4

_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// => 5

(static) set(object, path, value) → {Object}

Sets the value at `path` of `object`. If a portion of `path` doesn't exist, it's created. Arrays are created for missing index properties while objects are created for all other missing properties. Use `_.setWith` to customize `path` creation. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
Since:
  • 3.7.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// => 4

_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// => 5

(static) setWith(object, path, value, customizeropt) → {Object}

This method is like `_.set` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.0.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.setWith(object, '[0][1]', 'a', Object);
// => { '0': { '1': 'a' } }

(static) setWith(object, path, value, customizeropt) → {Object}

This method is like `_.set` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.0.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.setWith(object, '[0][1]', 'a', Object);
// => { '0': { '1': 'a' } }

(static) shuffle(collection) → {Array}

Creates an array of shuffled values, using a version of the [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
Parameters:
Name Type Description
collection Array | Object The collection to shuffle.
Since:
  • 0.1.0
Source:
Returns:
Returns the new shuffled array.
Type
Array
Example
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]

(static) shuffle(collection) → {Array}

Creates an array of shuffled values, using a version of the [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
Parameters:
Name Type Description
collection Array | Object The collection to shuffle.
Since:
  • 0.1.0
Source:
Returns:
Returns the new shuffled array.
Type
Array
Example
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) sortBy(collection, …iterateesopt) → {Array}

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees function | Array:.<function()> <optional>
<repeatable>
[_.identity] The iteratees to sort by.
Since:
  • 0.1.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) sortedIndex(array, value) → {number}

Uses a binary search to determine the lowest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 0.1.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedIndex([30, 50], 40);
// => 1

(static) sortedIndex(array, value) → {number}

Uses a binary search to determine the lowest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 0.1.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedIndex([30, 50], 40);
// => 1

(static) sortedIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 0

// The `_.property` iteratee shorthand.
_.sortedIndexBy(objects, { 'x': 4 }, 'x');
// => 0

(static) sortedIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 0

// The `_.property` iteratee shorthand.
_.sortedIndexBy(objects, { 'x': 4 }, 'x');
// => 0

(static) sortedIndexOf(array, value) → {number}

This method is like `_.indexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5);
// => 1

(static) sortedIndexOf(array, value) → {number}

This method is like `_.indexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5);
// => 1

(static) sortedLastIndex(array, value) → {number}

This method is like `_.sortedIndex` except that it returns the highest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 3.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5);
// => 4

(static) sortedLastIndex(array, value) → {number}

This method is like `_.sortedIndex` except that it returns the highest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 3.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5);
// => 4

(static) sortedLastIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedLastIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 1

// The `_.property` iteratee shorthand.
_.sortedLastIndexBy(objects, { 'x': 4 }, 'x');
// => 1

(static) sortedLastIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedLastIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 1

// The `_.property` iteratee shorthand.
_.sortedLastIndexBy(objects, { 'x': 4 }, 'x');
// => 1

(static) sortedLastIndexOf(array, value) → {number}

This method is like `_.lastIndexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5);
// => 3

(static) sortedLastIndexOf(array, value) → {number}

This method is like `_.lastIndexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5);
// => 3

(static) sortedUniq(array) → {Array}

This method is like `_.uniq` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniq([1, 1, 2]);
// => [1, 2]

(static) sortedUniq(array) → {Array}

This method is like `_.uniq` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniq([1, 1, 2]);
// => [1, 2]

(static) sortedUniqBy(array, iterateeopt) → {Array}

This method is like `_.uniqBy` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Attributes Description
array Array The array to inspect.
iteratee function <optional>
The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// => [1.1, 2.3]

(static) sortedUniqBy(array, iterateeopt) → {Array}

This method is like `_.uniqBy` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Attributes Description
array Array The array to inspect.
iteratee function <optional>
The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// => [1.1, 2.3]

(static) split(stringopt, separator, limitopt) → {Array}

Splits `string` by `separator`. **Note:** This method is based on [`String#split`](https://mdn.io/String/split).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to split.
separator RegExp | string The separator pattern to split by.
limit number <optional>
The length to truncate results to.
Since:
  • 4.0.0
Source:
Returns:
Returns the string segments.
Type
Array
Example
_.split('a-b-c', '-', 2);
// => ['a', 'b']

(static) split(stringopt, separator, limitopt) → {Array}

Splits `string` by `separator`. **Note:** This method is based on [`String#split`](https://mdn.io/String/split).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to split.
separator RegExp | string The separator pattern to split by.
limit number <optional>
The length to truncate results to.
Since:
  • 4.0.0
Source:
Returns:
Returns the string segments.
Type
Array
Example
_.split('a-b-c', '-', 2);
// => ['a', 'b']

(static) spread(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the create function and an array of arguments much like [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply). **Note:** This method is based on the [spread operator](https://mdn.io/spread_operator).
Parameters:
Name Type Attributes Default Description
func function The function to spread arguments over.
start number <optional>
0 The start position of the spread.
Since:
  • 3.2.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.spread(function(who, what) {
  return who + ' says ' + what;
});

say(['fred', 'hello']);
// => 'fred says hello'

var numbers = Promise.all([
  Promise.resolve(40),
  Promise.resolve(36)
]);

numbers.then(_.spread(function(x, y) {
  return x + y;
}));
// => a Promise of 76

(static) spread(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the create function and an array of arguments much like [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply). **Note:** This method is based on the [spread operator](https://mdn.io/spread_operator).
Parameters:
Name Type Attributes Default Description
func function The function to spread arguments over.
start number <optional>
0 The start position of the spread.
Since:
  • 3.2.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.spread(function(who, what) {
  return who + ' says ' + what;
});

say(['fred', 'hello']);
// => 'fred says hello'

var numbers = Promise.all([
  Promise.resolve(40),
  Promise.resolve(36)
]);

numbers.then(_.spread(function(x, y) {
  return x + y;
}));
// => a Promise of 76

(static) startsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` starts with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
0 The position to search from.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` starts with `target`, else `false`.
Type
boolean
Example
_.startsWith('abc', 'a');
// => true

_.startsWith('abc', 'b');
// => false

_.startsWith('abc', 'b', 1);
// => true

(static) startsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` starts with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
0 The position to search from.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` starts with `target`, else `false`.
Type
boolean
Example
_.startsWith('abc', 'a');
// => true

_.startsWith('abc', 'b');
// => false

_.startsWith('abc', 'b', 1);
// => true

(static) stubArray() → {Array}

This method returns a new empty array.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty array.
Type
Array
Example
var arrays = _.times(2, _.stubArray);

console.log(arrays);
// => [[], []]

console.log(arrays[0] === arrays[1]);
// => false

(static) stubArray() → {Array}

This method returns a new empty array.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty array.
Type
Array
Example
var arrays = _.times(2, _.stubArray);

console.log(arrays);
// => [[], []]

console.log(arrays[0] === arrays[1]);
// => false

(static) stubFalse() → {boolean}

This method returns `false`.
Since:
  • 4.13.0
Source:
Returns:
Returns `false`.
Type
boolean
Example
_.times(2, _.stubFalse);
// => [false, false]

(static) stubFalse() → {boolean}

This method returns `false`.
Since:
  • 4.13.0
Source:
Returns:
Returns `false`.
Type
boolean
Example
_.times(2, _.stubFalse);
// => [false, false]

(static) stubObject() → {Object}

This method returns a new empty object.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty object.
Type
Object
Example
var objects = _.times(2, _.stubObject);

console.log(objects);
// => [{}, {}]

console.log(objects[0] === objects[1]);
// => false

(static) stubObject() → {Object}

This method returns a new empty object.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty object.
Type
Object
Example
var objects = _.times(2, _.stubObject);

console.log(objects);
// => [{}, {}]

console.log(objects[0] === objects[1]);
// => false

(static) stubString() → {string}

This method returns an empty string.
Since:
  • 4.13.0
Source:
Returns:
Returns the empty string.
Type
string
Example
_.times(2, _.stubString);
// => ['', '']

(static) stubString() → {string}

This method returns an empty string.
Since:
  • 4.13.0
Source:
Returns:
Returns the empty string.
Type
string
Example
_.times(2, _.stubString);
// => ['', '']

(static) stubTrue() → {boolean}

This method returns `true`.
Since:
  • 4.13.0
Source:
Returns:
Returns `true`.
Type
boolean
Example
_.times(2, _.stubTrue);
// => [true, true]

(static) stubTrue() → {boolean}

This method returns `true`.
Since:
  • 4.13.0
Source:
Returns:
Returns `true`.
Type
boolean
Example
_.times(2, _.stubTrue);
// => [true, true]

(static) sum(array) → {number}

Computes the sum of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 3.4.0
Source:
Returns:
Returns the sum.
Type
number
Example
_.sum([4, 2, 8, 6]);
// => 20

(static) sum(array) → {number}

Computes the sum of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 3.4.0
Source:
Returns:
Returns the sum.
Type
number
Example
_.sum([4, 2, 8, 6]);
// => 20

(static) sumBy(array, iterateeopt) → {number}

This method is like `_.sum` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be summed. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the sum.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.sumBy(objects, function(o) { return o.n; });
// => 20

// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20

(static) sumBy(array, iterateeopt) → {number}

This method is like `_.sum` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be summed. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the sum.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.sumBy(objects, function(o) { return o.n; });
// => 20

// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20

(static) tail(array) → {Array}

Gets all but the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 4.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.tail([1, 2, 3]);
// => [2, 3]

(static) tail(array) → {Array}

Gets all but the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 4.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.tail([1, 2, 3]);
// => [2, 3]

(static) take(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.take([1, 2, 3]);
// => [1]

_.take([1, 2, 3], 2);
// => [1, 2]

_.take([1, 2, 3], 5);
// => [1, 2, 3]

_.take([1, 2, 3], 0);
// => []

(static) take(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.take([1, 2, 3]);
// => [1]

_.take([1, 2, 3], 2);
// => [1, 2]

_.take([1, 2, 3], 5);
// => [1, 2, 3]

_.take([1, 2, 3], 0);
// => []

(static) takeRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

_.takeRight([1, 2, 3], 0);
// => []

(static) takeRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

_.takeRight([1, 2, 3], 0);
// => []

(static) takeRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the end. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.takeRightWhile(users, function(o) { return !o.active; });
// => objects for ['fred', 'pebbles']

// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// => objects for ['fred', 'pebbles']

// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// => []

(static) takeRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the end. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.takeRightWhile(users, function(o) { return !o.active; });
// => objects for ['fred', 'pebbles']

// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// => objects for ['fred', 'pebbles']

// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// => []

(static) takeWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the beginning. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.takeWhile(users, function(o) { return !o.active; });
// => objects for ['barney', 'fred']

// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// => objects for ['barney', 'fred']

// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// => []

(static) takeWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the beginning. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.takeWhile(users, function(o) { return !o.active; });
// => objects for ['barney', 'fred']

// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// => objects for ['barney', 'fred']

// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// => []

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) template(stringopt, optionsopt) → {function}

Creates a compiled template function that can interpolate data properties in "interpolate" delimiters, HTML-escape interpolated data properties in "escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data properties may be accessed as free variables in the template. If a setting object is given, it takes precedence over `_.templateSettings` values. **Note:** In the development build `_.template` utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging. For more information on precompiling templates see [lodash's custom builds documentation](https://lodash.com/custom-builds). For more information on Chrome extension sandboxes see [Chrome's extensions documentation](https://developer.chrome.com/extensions/sandboxingEval).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The template string.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
escape RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL string <optional>
'lodash.templateSources[n]' The sourceURL of the compiled template.
variable string <optional>
'obj' The data object variable name.
Since:
  • 0.1.0
Source:
Returns:
Returns the compiled template function.
Type
function
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'

// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b>&lt;script&gt;</b>'

// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'

// Use the ES template literal delimiter as an "interpolate" delimiter.
// Disable support by replacing the "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'

// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'

// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.

// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// => function(data) {
//   var __t, __p = '';
//   __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
//   return __p;
// }

// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'

// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\
  var JST = {\
    "main": ' + _.template(mainText).source + '\
  };\
');

(static) template(stringopt, optionsopt) → {function}

Creates a compiled template function that can interpolate data properties in "interpolate" delimiters, HTML-escape interpolated data properties in "escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data properties may be accessed as free variables in the template. If a setting object is given, it takes precedence over `_.templateSettings` values. **Note:** In the development build `_.template` utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging. For more information on precompiling templates see [lodash's custom builds documentation](https://lodash.com/custom-builds). For more information on Chrome extension sandboxes see [Chrome's extensions documentation](https://developer.chrome.com/extensions/sandboxingEval).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The template string.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
escape RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL string <optional>
'templateSources[n]' The sourceURL of the compiled template.
variable string <optional>
'obj' The data object variable name.
Since:
  • 0.1.0
Source:
Returns:
Returns the compiled template function.
Type
function
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'

// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b>&lt;script&gt;</b>'

// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'

// Use the ES template literal delimiter as an "interpolate" delimiter.
// Disable support by replacing the "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'

// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'

// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.

// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// => function(data) {
//   var __t, __p = '';
//   __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
//   return __p;
// }

// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'

// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\
  var JST = {\
    "main": ' + _.template(mainText).source + '\
  };\
');

(static) throttle(func, waitopt, optionsopt) → {function}

Creates a throttled function that only invokes `func` at most once per every `wait` milliseconds. The throttled function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the throttled function. Subsequent calls to the throttled function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the throttled function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.throttle` and `_.debounce`.
Parameters:
Name Type Attributes Default Description
func function The function to throttle.
wait number <optional>
0 The number of milliseconds to throttle invocations to.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new throttled function.
Type
function
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));

// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);

// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);

(static) throttle(func, waitopt, optionsopt) → {function}

Creates a throttled function that only invokes `func` at most once per every `wait` milliseconds. The throttled function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the throttled function. Subsequent calls to the throttled function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the throttled function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.throttle` and `_.debounce`.
Parameters:
Name Type Attributes Default Description
func function The function to throttle.
wait number <optional>
0 The number of milliseconds to throttle invocations to.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new throttled function.
Type
function
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));

// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);

// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) times(n, iterateeopt) → {Array}

Invokes the iteratee `n` times, returning an array of the results of each invocation. The iteratee is invoked with one argument; (index).
Parameters:
Name Type Attributes Default Description
n number The number of times to invoke `iteratee`.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of results.
Type
Array
Example
_.times(3, String);
// => ['0', '1', '2']

 _.times(4, _.constant(0));
// => [0, 0, 0, 0]

(static) times(n, iterateeopt) → {Array}

Invokes the iteratee `n` times, returning an array of the results of each invocation. The iteratee is invoked with one argument; (index).
Parameters:
Name Type Attributes Default Description
n number The number of times to invoke `iteratee`.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of results.
Type
Array
Example
_.times(3, String);
// => ['0', '1', '2']

 _.times(4, _.constant(0));
// => [0, 0, 0, 0]

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toLength(value) → {number}

Converts `value` to an integer suitable for use as the length of an array-like object. **Note:** This method is based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toLength(3.2);
// => 3

_.toLength(Number.MIN_VALUE);
// => 0

_.toLength(Infinity);
// => 4294967295

_.toLength('3.2');
// => 3

(static) toLength(value) → {number}

Converts `value` to an integer suitable for use as the length of an array-like object. **Note:** This method is based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toLength(3.2);
// => 3

_.toLength(Number.MIN_VALUE);
// => 0

_.toLength(Infinity);
// => 4294967295

_.toLength('3.2');
// => 3

(static) toLower(stringopt) → {string}

Converts `string`, as a whole, to lower case just like [String#toLowerCase](https://mdn.io/toLowerCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the lower cased string.
Type
string
Example
_.toLower('--Foo-Bar--');
// => '--foo-bar--'

_.toLower('fooBar');
// => 'foobar'

_.toLower('__FOO_BAR__');
// => '__foo_bar__'

(static) toLower(stringopt) → {string}

Converts `string`, as a whole, to lower case just like [String#toLowerCase](https://mdn.io/toLowerCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the lower cased string.
Type
string
Example
_.toLower('--Foo-Bar--');
// => '--foo-bar--'

_.toLower('fooBar');
// => 'foobar'

_.toLower('__FOO_BAR__');
// => '__foo_bar__'

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toPath(value) → {Array}

Converts `value` to a property path array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the new property path array.
Type
Array
Example
_.toPath('a.b.c');
// => ['a', 'b', 'c']

_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']

(static) toPath(value) → {Array}

Converts `value` to a property path array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the new property path array.
Type
Array
Example
_.toPath('a.b.c');
// => ['a', 'b', 'c']

_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']

(static) toPlainObject(value) → {Object}

Converts `value` to a plain object flattening inherited enumerable string keyed properties of `value` to own properties of the plain object.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 3.0.0
Source:
Returns:
Returns the converted plain object.
Type
Object
Example
function Foo() {
  this.b = 2;
}

Foo.prototype.c = 3;

_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }

_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }

(static) toPlainObject(value) → {Object}

Converts `value` to a plain object flattening inherited enumerable string keyed properties of `value` to own properties of the plain object.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 3.0.0
Source:
Returns:
Returns the converted plain object.
Type
Object
Example
function Foo() {
  this.b = 2;
}

Foo.prototype.c = 3;

_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }

_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }

(static) toSafeInteger(value) → {number}

Converts `value` to a safe integer. A safe integer can be compared and represented correctly.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toSafeInteger(3.2);
// => 3

_.toSafeInteger(Number.MIN_VALUE);
// => 0

_.toSafeInteger(Infinity);
// => 9007199254740991

_.toSafeInteger('3.2');
// => 3

(static) toSafeInteger(value) → {number}

Converts `value` to a safe integer. A safe integer can be compared and represented correctly.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toSafeInteger(3.2);
// => 3

_.toSafeInteger(Number.MIN_VALUE);
// => 0

_.toSafeInteger(Infinity);
// => 9007199254740991

_.toSafeInteger('3.2');
// => 3

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toUpper(stringopt) → {string}

Converts `string`, as a whole, to upper case just like [String#toUpperCase](https://mdn.io/toUpperCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the upper cased string.
Type
string
Example
_.toUpper('--foo-bar--');
// => '--FOO-BAR--'

_.toUpper('fooBar');
// => 'FOOBAR'

_.toUpper('__foo_bar__');
// => '__FOO_BAR__'

(static) toUpper(stringopt) → {string}

Converts `string`, as a whole, to upper case just like [String#toUpperCase](https://mdn.io/toUpperCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the upper cased string.
Type
string
Example
_.toUpper('--foo-bar--');
// => '--FOO-BAR--'

_.toUpper('fooBar');
// => 'FOOBAR'

_.toUpper('__foo_bar__');
// => '__FOO_BAR__'

(static) transform(object, iterateeopt, accumulatoropt) → {*}

An alternative to `_.reduce`; this method transforms `object` to a new `accumulator` object which is the result of running each of its own enumerable string keyed properties thru `iteratee`, with each invocation potentially mutating the `accumulator` object. If `accumulator` is not provided, a new object with the same `[[Prototype]]` will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The custom accumulator value.
Since:
  • 1.3.0
Source:
Returns:
Returns the accumulated value.
Type
*
Example
_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
}, []);
// => [4, 9]

_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
}, {});
// => { '1': ['a', 'c'], '2': ['b'] }

(static) transform(object, iterateeopt, accumulatoropt) → {*}

An alternative to `_.reduce`; this method transforms `object` to a new `accumulator` object which is the result of running each of its own enumerable string keyed properties thru `iteratee`, with each invocation potentially mutating the `accumulator` object. If `accumulator` is not provided, a new object with the same `[[Prototype]]` will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The custom accumulator value.
Since:
  • 1.3.0
Source:
Returns:
Returns the accumulated value.
Type
*
Example
_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
}, []);
// => [4, 9]

_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
}, {});
// => { '1': ['a', 'c'], '2': ['b'] }

(static) trim(stringopt, charsopt) → {string}

Removes leading and trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 3.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trim('  abc  ');
// => 'abc'

_.trim('-_-abc-_-', '_-');
// => 'abc'

_.map(['  foo  ', '  bar  '], _.trim);
// => ['foo', 'bar']

(static) trim(stringopt, charsopt) → {string}

Removes leading and trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 3.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trim('  abc  ');
// => 'abc'

_.trim('-_-abc-_-', '_-');
// => 'abc'

_.map(['  foo  ', '  bar  '], _.trim);
// => ['foo', 'bar']

(static) trimEnd(stringopt, charsopt) → {string}

Removes trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimEnd('  abc  ');
// => '  abc'

_.trimEnd('-_-abc-_-', '_-');
// => '-_-abc'

(static) trimEnd(stringopt, charsopt) → {string}

Removes trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimEnd('  abc  ');
// => '  abc'

_.trimEnd('-_-abc-_-', '_-');
// => '-_-abc'

(static) trimStart(stringopt, charsopt) → {string}

Removes leading whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimStart('  abc  ');
// => 'abc  '

_.trimStart('-_-abc-_-', '_-');
// => 'abc-_-'

(static) trimStart(stringopt, charsopt) → {string}

Removes leading whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimStart('  abc  ');
// => 'abc  '

_.trimStart('-_-abc-_-', '_-');
// => 'abc-_-'

(static) truncate(stringopt, optionsopt) → {string}

Truncates `string` if it's longer than the given maximum string length. The last characters of the truncated string are replaced with the omission string which defaults to "...".
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to truncate.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
length number <optional>
30 The maximum string length.
omission string <optional>
'...' The string to indicate text is omitted.
separator RegExp | string <optional>
The separator pattern to truncate to.
Since:
  • 4.0.0
Source:
Returns:
Returns the truncated string.
Type
string
Example
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': ' '
});
// => 'hi-diddly-ho there,...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': /,? +/
});
// => 'hi-diddly-ho there...'

_.truncate('hi-diddly-ho there, neighborino', {
  'omission': ' [...]'
});
// => 'hi-diddly-ho there, neig [...]'

(static) truncate(stringopt, optionsopt) → {string}

Truncates `string` if it's longer than the given maximum string length. The last characters of the truncated string are replaced with the omission string which defaults to "...".
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to truncate.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
length number <optional>
30 The maximum string length.
omission string <optional>
'...' The string to indicate text is omitted.
separator RegExp | string <optional>
The separator pattern to truncate to.
Since:
  • 4.0.0
Source:
Returns:
Returns the truncated string.
Type
string
Example
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': ' '
});
// => 'hi-diddly-ho there,...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': /,? +/
});
// => 'hi-diddly-ho there...'

_.truncate('hi-diddly-ho there, neighborino', {
  'omission': ' [...]'
});
// => 'hi-diddly-ho there, neig [...]'

(static) unary(func) → {function}

Creates a function that accepts up to one argument, ignoring any additional arguments.
Parameters:
Name Type Description
func function The function to cap arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// => [6, 8, 10]

(static) unary(func) → {function}

Creates a function that accepts up to one argument, ignoring any additional arguments.
Parameters:
Name Type Description
func function The function to cap arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// => [6, 8, 10]

(static) unescape(stringopt) → {string}

The inverse of `_.escape`; this method converts the HTML entities `&`, `<`, `>`, `"`, and `'` in `string` to their corresponding characters. **Note:** No other HTML entities are unescaped. To unescape additional HTML entities use a third-party library like [_he_](https://mths.be/he).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to unescape.
Since:
  • 0.6.0
Source:
Returns:
Returns the unescaped string.
Type
string
Example
_.unescape('fred, barney, &amp; pebbles');
// => 'fred, barney, & pebbles'

(static) unescape(stringopt) → {string}

The inverse of `_.escape`; this method converts the HTML entities `&`, `<`, `>`, `"`, and `'` in `string` to their corresponding characters. **Note:** No other HTML entities are unescaped. To unescape additional HTML entities use a third-party library like [_he_](https://mths.be/he).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to unescape.
Since:
  • 0.6.0
Source:
Returns:
Returns the unescaped string.
Type
string
Example
_.unescape('fred, barney, &amp; pebbles');
// => 'fred, barney, & pebbles'

(static) uniq(array) → {Array}

Creates a duplicate-free version of an array, using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniq([2, 1, 2]);
// => [2, 1]

(static) uniq(array) → {Array}

Creates a duplicate-free version of an array, using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniq([2, 1, 2]);
// => [2, 1]

(static) uniqBy(array, iterateeopt) → {Array}

This method is like `_.uniq` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which uniqueness is computed. The order of result values is determined by the order they occur in the array. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) uniqBy(array, iterateeopt) → {Array}

This method is like `_.uniq` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which uniqueness is computed. The order of result values is determined by the order they occur in the array. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) uniqWith(array, comparatoropt) → {Array}

This method is like `_.uniq` except that it accepts `comparator` which is invoked to compare elements of `array`. The order of result values is determined by the order they occur in the array.The comparator is invoked with two arguments: (arrVal, othVal).
Parameters:
Name Type Attributes Description
array Array The array to inspect.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

(static) uniqWith(array, comparatoropt) → {Array}

This method is like `_.uniq` except that it accepts `comparator` which is invoked to compare elements of `array`. The order of result values is determined by the order they occur in the array.The comparator is invoked with two arguments: (arrVal, othVal).
Parameters:
Name Type Attributes Description
array Array The array to inspect.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) unset(object, path) → {boolean}

Removes the property at `path` of `object`. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to unset.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the property is deleted, else `false`.
Type
boolean
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

_.unset(object, ['a', '0', 'b', 'c']);
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

(static) unset(object, path) → {boolean}

Removes the property at `path` of `object`. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to unset.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the property is deleted, else `false`.
Type
boolean
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

_.unset(object, ['a', '0', 'b', 'c']);
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

(static) unzip(array) → {Array}

This method is like `_.zip` except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.
Parameters:
Name Type Description
array Array The array of grouped elements to process.
Since:
  • 1.2.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

_.unzip(zipped);
// => [['a', 'b'], [1, 2], [true, false]]

(static) unzip(array) → {Array}

This method is like `_.zip` except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.
Parameters:
Name Type Description
array Array The array of grouped elements to process.
Since:
  • 1.2.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

_.unzip(zipped);
// => [['a', 'b'], [1, 2], [true, false]]

(static) unzipWith(array, iterateeopt) → {Array}

This method is like `_.unzip` except that it accepts `iteratee` to specify how regrouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Parameters:
Name Type Attributes Default Description
array Array The array of grouped elements to process.
iteratee function <optional>
_.identity The function to combine regrouped values.
Since:
  • 3.8.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]

_.unzipWith(zipped, _.add);
// => [3, 30, 300]

(static) unzipWith(array, iterateeopt) → {Array}

This method is like `_.unzip` except that it accepts `iteratee` to specify how regrouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Parameters:
Name Type Attributes Default Description
array Array The array of grouped elements to process.
iteratee function <optional>
_.identity The function to combine regrouped values.
Since:
  • 3.8.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]

_.unzipWith(zipped, _.add);
// => [3, 30, 300]

(static) update(object, path, updater) → {Object}

This method is like `_.set` except that accepts `updater` to produce the value to set. Use `_.updateWith` to customize `path` creation. The `updater` is invoked with one argument: (value). **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// => 9

_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// => 0

(static) update(object, path, updater) → {Object}

This method is like `_.set` except that accepts `updater` to produce the value to set. Use `_.updateWith` to customize `path` creation. The `updater` is invoked with one argument: (value). **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// => 9

_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// => 0

(static) updateWith(object, path, updater, customizeropt) → {Object}

This method is like `_.update` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.updateWith(object, '[0][1]', _.constant('a'), Object);
// => { '0': { '1': 'a' } }

(static) updateWith(object, path, updater, customizeropt) → {Object}

This method is like `_.update` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.updateWith(object, '[0][1]', _.constant('a'), Object);
// => { '0': { '1': 'a' } }

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) valuesIn(object) → {Array}

Creates an array of the own and inherited enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)

(static) valuesIn(object) → {Array}

Creates an array of the own and inherited enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)

(static) words(stringopt, patternopt) → {Array}

Splits `string` into an array of its words.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
pattern RegExp | string <optional>
The pattern to match words.
Since:
  • 3.0.0
Source:
Returns:
Returns the words of `string`.
Type
Array
Example
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']

_.words('fred, barney, & pebbles', /[^, ]+/g);
// => ['fred', 'barney', '&', 'pebbles']

(static) words(stringopt, patternopt) → {Array}

Splits `string` into an array of its words.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
pattern RegExp | string <optional>
The pattern to match words.
Since:
  • 3.0.0
Source:
Returns:
Returns the words of `string`.
Type
Array
Example
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']

_.words('fred, barney, & pebbles', /[^, ]+/g);
// => ['fred', 'barney', '&', 'pebbles']

(static) wrap(value, wrapperopt) → {function}

Creates a function that provides `value` to `wrapper` as its first argument. Any additional arguments provided to the function are appended to those provided to the `wrapper`. The wrapper is invoked with the `this` binding of the created function.
Parameters:
Name Type Attributes Default Description
value * The value to wrap.
wrapper function <optional>
identity The wrapper function.
Since:
  • 0.1.0
Source:
Returns:
Returns the new function.
Type
function
Example
var p = _.wrap(_.escape, function(func, text) {
  return '<p>' + func(text) + '</p>';
});

p('fred, barney, & pebbles');
// => '<p>fred, barney, &amp; pebbles</p>'

(static) wrap(value, wrapperopt) → {function}

Creates a function that provides `value` to `wrapper` as its first argument. Any additional arguments provided to the function are appended to those provided to the `wrapper`. The wrapper is invoked with the `this` binding of the created function.
Parameters:
Name Type Attributes Default Description
value * The value to wrap.
wrapper function <optional>
identity The wrapper function.
Since:
  • 0.1.0
Source:
Returns:
Returns the new function.
Type
function
Example
var p = _.wrap(_.escape, function(func, text) {
  return '<p>' + func(text) + '</p>';
});

p('fred, barney, & pebbles');
// => '<p>fred, barney, &amp; pebbles</p>'

(static) zipObject(propsopt, valuesopt) → {Object}

This method is like `_.fromPairs` except that it accepts two arrays, one of property identifiers and one of corresponding values.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 0.4.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }

(static) zipObject(propsopt, valuesopt) → {Object}

This method is like `_.fromPairs` except that it accepts two arrays, one of property identifiers and one of corresponding values.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 0.4.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }

(static) zipObjectDeep(propsopt, valuesopt) → {Object}

This method is like `_.zipObject` except that it supports property paths.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 4.1.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }

(static) zipObjectDeep(propsopt, valuesopt) → {Object}

This method is like `_.zipObject` except that it supports property paths.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 4.1.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }

_(value) → {Object}

new _(value) → {Object}

Creates a `lodash` object which wraps `value` to enable implicit method chain sequences. Methods that operate on and return arrays, collections, and functions can be chained together. Methods that retrieve a single value or may return a primitive value will automatically end the chain sequence and return the unwrapped value. Otherwise, the value must be unwrapped with `_#value`. Explicit chain sequences, which must be unwrapped with `_#value`, may be enabled using `_.chain`. The execution of chained methods is lazy, that is, it's deferred until `_#value` is implicitly or explicitly called. Lazy evaluation allows several methods to support shortcut fusion. Shortcut fusion is an optimization to merge iteratee calls; this avoids the creation of intermediate arrays and can greatly reduce the number of iteratee executions. Sections of a chain sequence qualify for shortcut fusion if the section is applied to an array and iteratees accept only one argument. The heuristic for whether a section qualifies for shortcut fusion is subject to change. Chaining is supported in custom builds as long as the `_#value` method is directly or indirectly included in the build. In addition to lodash methods, wrappers have `Array` and `String` methods. The wrapper `Array` methods are: `concat`, `join`, `pop`, `push`, `shift`, `sort`, `splice`, and `unshift` The wrapper `String` methods are: `replace` and `split` The wrapper methods that support shortcut fusion are: `at`, `compact`, `drop`, `dropRight`, `dropWhile`, `filter`, `find`, `findLast`, `head`, `initial`, `last`, `map`, `reject`, `reverse`, `slice`, `tail`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, and `toArray` The chainable wrapper methods are: `after`, `ary`, `assign`, `assignIn`, `assignInWith`, `assignWith`, `at`, `before`, `bind`, `bindAll`, `bindKey`, `castArray`, `chain`, `chunk`, `commit`, `compact`, `concat`, `conforms`, `constant`, `countBy`, `create`, `curry`, `debounce`, `defaults`, `defaultsDeep`, `defer`, `delay`, `difference`, `differenceBy`, `differenceWith`, `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `extend`, `extendWith`, `fill`, `filter`, `flatMap`, `flatMapDeep`, `flatMapDepth`, `flatten`, `flattenDeep`, `flattenDepth`, `flip`, `flow`, `flowRight`, `fromPairs`, `functions`, `functionsIn`, `groupBy`, `initial`, `intersection`, `intersectionBy`, `intersectionWith`, `invert`, `invertBy`, `invokeMap`, `iteratee`, `keyBy`, `keys`, `keysIn`, `map`, `mapKeys`, `mapValues`, `matches`, `matchesProperty`, `memoize`, `merge`, `mergeWith`, `method`, `methodOf`, `mixin`, `negate`, `nthArg`, `omit`, `omitBy`, `once`, `orderBy`, `over`, `overArgs`, `overEvery`, `overSome`, `partial`, `partialRight`, `partition`, `pick`, `pickBy`, `plant`, `property`, `propertyOf`, `pull`, `pullAll`, `pullAllBy`, `pullAllWith`, `pullAt`, `push`, `range`, `rangeRight`, `rearg`, `reject`, `remove`, `rest`, `reverse`, `sampleSize`, `set`, `setWith`, `shuffle`, `slice`, `sort`, `sortBy`, `splice`, `spread`, `tail`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, `tap`, `throttle`, `thru`, `toArray`, `toPairs`, `toPairsIn`, `toPath`, `toPlainObject`, `transform`, `unary`, `union`, `unionBy`, `unionWith`, `uniq`, `uniqBy`, `uniqWith`, `unset`, `unshift`, `unzip`, `unzipWith`, `update`, `updateWith`, `values`, `valuesIn`, `without`, `wrap`, `xor`, `xorBy`, `xorWith`, `zip`, `zipObject`, `zipObjectDeep`, and `zipWith` The wrapper methods that are **not** chainable by default are: `add`, `attempt`, `camelCase`, `capitalize`, `ceil`, `clamp`, `clone`, `cloneDeep`, `cloneDeepWith`, `cloneWith`, `conformsTo`, `deburr`, `defaultTo`, `divide`, `each`, `eachRight`, `endsWith`, `eq`, `escape`, `escapeRegExp`, `every`, `find`, `findIndex`, `findKey`, `findLast`, `findLastIndex`, `findLastKey`, `first`, `floor`, `forEach`, `forEachRight`, `forIn`, `forInRight`, `forOwn`, `forOwnRight`, `get`, `gt`, `gte`, `has`, `hasIn`, `head`, `identity`, `includes`, `indexOf`, `inRange`, `invoke`, `isArguments`, `isArray`, `isArrayBuffer`, `isArrayLike`, `isArrayLikeObject`, `isBoolean`, `isBuffer`, `isDate`, `isElement`, `isEmpty`, `isEqual`, `isEqualWith`, `isError`, `isFinite`, `isFunction`, `isInteger`, `isLength`, `isMap`, `isMatch`, `isMatchWith`, `isNaN`, `isNative`, `isNil`, `isNull`, `isNumber`, `isObject`, `isObjectLike`, `isPlainObject`, `isRegExp`, `isSafeInteger`, `isSet`, `isString`, `isUndefined`, `isTypedArray`, `isWeakMap`, `isWeakSet`, `join`, `kebabCase`, `last`, `lastIndexOf`, `lowerCase`, `lowerFirst`, `lt`, `lte`, `max`, `maxBy`, `mean`, `meanBy`, `min`, `minBy`, `multiply`, `noConflict`, `noop`, `now`, `nth`, `pad`, `padEnd`, `padStart`, `parseInt`, `pop`, `random`, `reduce`, `reduceRight`, `repeat`, `result`, `round`, `runInContext`, `sample`, `shift`, `size`, `snakeCase`, `some`, `sortedIndex`, `sortedIndexBy`, `sortedLastIndex`, `sortedLastIndexBy`, `startCase`, `startsWith`, `stubArray`, `stubFalse`, `stubObject`, `stubString`, `stubTrue`, `subtract`, `sum`, `sumBy`, `template`, `times`, `toFinite`, `toInteger`, `toJSON`, `toLength`, `toLower`, `toNumber`, `toSafeInteger`, `toString`, `toUpper`, `trim`, `trimEnd`, `trimStart`, `truncate`, `unescape`, `uniqueId`, `upperCase`, `upperFirst`, `value`, and `words`
Parameters:
Name Type Description
value * The value to wrap in a `lodash` instance.
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2, 3]);

// Returns an unwrapped value.
wrapped.reduce(_.add);
// => 6

// Returns a wrapped value.
var squares = wrapped.map(square);

_.isArray(squares);
// => false

_.isArray(squares.value());
// => true

Members

(static) add

Adds two numbers.
Since:
  • 3.4.0
Source:
Example
_.add(6, 4);
// => 10

(static) add

Adds two numbers.
Since:
  • 3.4.0
Source:
Example
_.add(6, 4);
// => 10

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object` and is loosely based on [`Object.assign`](https://mdn.io/Object/assign).
Since:
  • 0.10.0
Source:
See:
  • _.assignIn
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assign({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3 }

(static) assignWith

This method is like `_.assign` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
  • _.assignInWith
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) assignWith

This method is like `_.assign` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
  • _.assignInWith
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) at

Creates an array of values corresponding to `paths` of `object`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_.at(object, ['a[0].b.c', 'a[1]']);
// => [3, 4]

(static) at

This method is the wrapper version of `_.at`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]

(static) at

Creates an array of values corresponding to `paths` of `object`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_.at(object, ['a[0].b.c', 'a[1]']);
// => [3, 4]

(static) at

This method is the wrapper version of `_.at`.
Since:
  • 1.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };

_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]

(static) attempt

Attempts to invoke `func`, returning either the result or the caught error object. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 3.0.0
Source:
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
  return document.querySelectorAll(selector);
}, '>_>');

if (_.isError(elements)) {
  elements = [];
}

(static) attempt

Attempts to invoke `func`, returning either the result or the caught error object. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 3.0.0
Source:
Example
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
  return document.querySelectorAll(selector);
}, '>_>');

if (_.isError(elements)) {
  elements = [];
}

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bind

Creates a function that invokes `func` with the `this` binding of `thisArg` and `partials` prepended to the arguments it receives. The `_.bind.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** Unlike native `Function#bind`, this method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

var object = { 'user': 'fred' };

var bound = _.bind(greet, object, 'hi');
bound('!');
// => 'hi fred!'

// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// => 'hi fred!'

(static) bindAll

Binds methods of an object to the object itself, overwriting the existing method. **Note:** This method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
var view = {
  'label': 'docs',
  'click': function() {
    console.log('clicked ' + this.label);
  }
};

_.bindAll(view, ['click']);
jQuery(element).on('click', view.click);
// => Logs 'clicked docs' when clicked.

(static) bindAll

Binds methods of an object to the object itself, overwriting the existing method. **Note:** This method doesn't set the "length" property of bound functions.
Since:
  • 0.1.0
Source:
Example
var view = {
  'label': 'docs',
  'click': function() {
    console.log('clicked ' + this.label);
  }
};

_.bindAll(view, ['click']);
jQuery(element).on('click', view.click);
// => Logs 'clicked docs' when clicked.

(static) bindKey

Creates a function that invokes the method at `object[key]` with `partials` prepended to the arguments it receives. This method differs from `_.bind` by allowing bound functions to reference methods that may be redefined or don't yet exist. See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern) for more details. The `_.bindKey.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments.
Since:
  • 0.10.0
Source:
Example
var object = {
  'user': 'fred',
  'greet': function(greeting, punctuation) {
    return greeting + ' ' + this.user + punctuation;
  }
};

var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// => 'hi fred!'

object.greet = function(greeting, punctuation) {
  return greeting + 'ya ' + this.user + punctuation;
};

bound('!');
// => 'hiya fred!'

// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// => 'hiya fred!'

(static) bindKey

Creates a function that invokes the method at `object[key]` with `partials` prepended to the arguments it receives. This method differs from `_.bind` by allowing bound functions to reference methods that may be redefined or don't yet exist. See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern) for more details. The `_.bindKey.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments.
Since:
  • 0.10.0
Source:
Example
var object = {
  'user': 'fred',
  'greet': function(greeting, punctuation) {
    return greeting + ' ' + this.user + punctuation;
  }
};

var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// => 'hi fred!'

object.greet = function(greeting, punctuation) {
  return greeting + 'ya ' + this.user + punctuation;
};

bound('!');
// => 'hiya fred!'

// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// => 'hiya fred!'

(static) camelCase

Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
Since:
  • 3.0.0
Source:
Example
_.camelCase('Foo Bar');
// => 'fooBar'

_.camelCase('--foo-bar--');
// => 'fooBar'

_.camelCase('__FOO_BAR__');
// => 'fooBar'

(static) camelCase

Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
Since:
  • 3.0.0
Source:
Example
_.camelCase('Foo Bar');
// => 'fooBar'

_.camelCase('--foo-bar--');
// => 'fooBar'

_.camelCase('__FOO_BAR__');
// => 'fooBar'

(static) ceil

Computes `number` rounded up to `precision`.
Since:
  • 3.10.0
Source:
Example
_.ceil(4.006);
// => 5

_.ceil(6.004, 2);
// => 6.01

_.ceil(6040, -2);
// => 6100

(static) ceil

Computes `number` rounded up to `precision`.
Since:
  • 3.10.0
Source:
Example
_.ceil(4.006);
// => 5

_.ceil(6.004, 2);
// => 6.01

_.ceil(6040, -2);
// => 6100

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) chain

Creates a `lodash` wrapper instance with explicit method chain sequences enabled.
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }

// A sequence with explicit chaining.
_(users)
  .chain()
  .head()
  .pick('user')
  .value();
// => { 'user': 'barney' }

(static) commit

Executes the chain sequence and returns the wrapped result.
Since:
  • 3.2.0
Source:
Example
var array = [1, 2];
var wrapped = _(array).push(3);

console.log(array);
// => [1, 2]

wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]

wrapped.last();
// => 3

console.log(array);
// => [1, 2, 3]

(static) commit

Executes the chain sequence and returns the wrapped result.
Since:
  • 3.2.0
Source:
Example
var array = [1, 2];
var wrapped = _(array).push(3);

console.log(array);
// => [1, 2]

wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]

wrapped.last();
// => 3

console.log(array);
// => [1, 2, 3]

(static) countBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the number of times the key was returned by `iteratee`. The iteratee is invoked with one argument: (value).
Since:
  • 0.5.0
Source:
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }

// The `_.property` iteratee shorthand.
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }

(static) countBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the number of times the key was returned by `iteratee`. The iteratee is invoked with one argument: (value).
Since:
  • 0.5.0
Source:
Example
_.countBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': 1, '6': 2 }

// The `_.property` iteratee shorthand.
_.countBy(['one', 'two', 'three'], 'length');
// => { '3': 2, '5': 1 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaults

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to `undefined`. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored. **Note:** This method mutates `object`.
Since:
  • 0.1.0
Source:
See:
Example
_.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) defaultsDeep

This method is like `_.defaults` except that it recursively assigns default properties. **Note:** This method mutates `object`.
Since:
  • 3.10.0
Source:
See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } });
// => { 'a': { 'b': 2, 'c': 3 } }

(static) defaultsDeep

This method is like `_.defaults` except that it recursively assigns default properties. **Note:** This method mutates `object`.
Since:
  • 3.10.0
Source:
See:
Example
_.defaultsDeep({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } });
// => { 'a': { 'b': 2, 'c': 3 } }

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) defer

Defers invoking the `func` until the current call stack has cleared. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.defer(function(text) {
  console.log(text);
}, 'deferred');
// => Logs 'deferred' after one millisecond.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) delay

Invokes `func` after `wait` milliseconds. Any additional arguments are provided to `func` when it's invoked.
Since:
  • 0.1.0
Source:
Example
_.delay(function(text) {
  console.log(text);
}, 1000, 'later');
// => Logs 'later' after one second.

(static) difference

Creates an array of `array` values not included in the other given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array. **Note:** Unlike `_.pullAll`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.without, _.xor
Example
_.difference([2, 1], [2, 3]);
// => [1]

(static) difference

Creates an array of `array` values not included in the other given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array. **Note:** Unlike `_.pullAll`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.without, _.xor
Example
_.difference([2, 1], [2, 3]);
// => [1]

(static) differenceBy

This method is like `_.difference` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.pullAllBy`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2]

// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) differenceBy

This method is like `_.difference` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.pullAllBy`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
_.differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2]

// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) differenceWith

This method is like `_.difference` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.pullAllWith`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];

_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

(static) differenceWith

This method is like `_.difference` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.pullAllWith`, this method returns a new array.
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];

_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

(static) divide

Divide two numbers.
Since:
  • 4.7.0
Source:
Example
_.divide(6, 4);
// => 1.5

(static) divide

Divide two numbers.
Since:
  • 4.7.0
Source:
Example
_.divide(6, 4);
// => 1.5

(static) entries

Creates an array of own enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)

(static) entries

Creates an array of own enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)

(static) entriesIn

Creates an array of own and inherited enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)

(static) entriesIn

Creates an array of own and inherited enumerable string keyed-value pairs for `object` which can be consumed by `_.fromPairs`. If `object` is a map or set, its entries are returned.
Since:
  • 4.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 3]] (iteration order is not guaranteed)

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extend

This method is like `_.assign` except that it iterates over own and inherited source properties. **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function Foo() {
  this.a = 1;
}

function Bar() {
  this.c = 3;
}

Foo.prototype.b = 2;
Bar.prototype.d = 4;

_.assignIn({ 'a': 0 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4 }

(static) extendWith

This method is like `_.assignIn` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignInWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) extendWith

This method is like `_.assignIn` except that it accepts `customizer` which is invoked to produce the assigned values. If `customizer` returns `undefined`, assignment is handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, key, object, source). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
See:
Example
function customizer(objValue, srcValue) {
  return _.isUndefined(objValue) ? srcValue : objValue;
}

var defaults = _.partialRight(_.assignInWith, customizer);

defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) find

Iterates over elements of `collection`, returning the first element `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': true },
  { 'user': 'fred',    'age': 40, 'active': false },
  { 'user': 'pebbles', 'age': 1,  'active': true }
];

_.find(users, function(o) { return o.age < 40; });
// => object for 'barney'

// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// => object for 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// => object for 'fred'

// The `_.property` iteratee shorthand.
_.find(users, 'active');
// => object for 'barney'

(static) findLast

This method is like `_.find` except that it iterates over elements of `collection` from right to left.
Since:
  • 2.0.0
Source:
Example
_.findLast([1, 2, 3, 4], function(n) {
  return n % 2 == 1;
});
// => 3

(static) findLast

This method is like `_.find` except that it iterates over elements of `collection` from right to left.
Since:
  • 2.0.0
Source:
Example
_.findLast([1, 2, 3, 4], function(n) {
  return n % 2 == 1;
});
// => 3

(static) floor

Computes `number` rounded down to `precision`.
Since:
  • 3.10.0
Source:
Example
_.floor(4.006);
// => 4

_.floor(0.046, 2);
// => 0.04

_.floor(4060, -2);
// => 4000

(static) floor

Computes `number` rounded down to `precision`.
Since:
  • 3.10.0
Source:
Example
_.floor(4.006);
// => 4

_.floor(0.046, 2);
// => 0.04

_.floor(4060, -2);
// => 4000

(static) flow

Creates a function that returns the result of invoking the given functions with the `this` binding of the created function, where each successive invocation is supplied the return value of the previous.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flow([_.add, square]);
addSquare(1, 2);
// => 9

(static) flow

Creates a function that returns the result of invoking the given functions with the `this` binding of the created function, where each successive invocation is supplied the return value of the previous.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flow([_.add, square]);
addSquare(1, 2);
// => 9

(static) flowRight

This method is like `_.flow` except that it creates a function that invokes the given functions from right to left.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flowRight([square, _.add]);
addSquare(1, 2);
// => 9

(static) flowRight

This method is like `_.flow` except that it creates a function that invokes the given functions from right to left.
Since:
  • 3.0.0
Source:
See:
Example
function square(n) {
  return n * n;
}

var addSquare = _.flowRight([square, _.add]);
addSquare(1, 2);
// => 9

(static) groupBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }

// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

(static) groupBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The order of grouped values is determined by the order they occur in `collection`. The corresponding value of each key is an array of elements responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// => { '4': [4.2], '6': [6.1, 6.3] }

// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// => { '3': ['one', 'two'], '5': ['three'] }

(static) gt

Checks if `value` is greater than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gt(3, 1);
// => true

_.gt(3, 3);
// => false

_.gt(1, 3);
// => false

(static) gt

Checks if `value` is greater than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gt(3, 1);
// => true

_.gt(3, 3);
// => false

_.gt(1, 3);
// => false

(static) gte

Checks if `value` is greater than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gte(3, 1);
// => true

_.gte(3, 3);
// => true

_.gte(1, 3);
// => false

(static) gte

Checks if `value` is greater than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.gte(3, 1);
// => true

_.gte(3, 3);
// => true

_.gte(1, 3);
// => false

(static) intersection

Creates an array of unique values that are included in all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array.
Since:
  • 0.1.0
Source:
Example
_.intersection([2, 1], [2, 3]);
// => [2]

(static) intersection

Creates an array of unique values that are included in all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. The order and references of result values are determined by the first array.
Since:
  • 0.1.0
Source:
Example
_.intersection([2, 1], [2, 3]);
// => [2]

(static) intersectionBy

This method is like `_.intersection` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [2.1]

// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }]

(static) intersectionBy

This method is like `_.intersection` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which they're compared. The order and references of result values are determined by the first array. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [2.1]

// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }]

(static) intersectionWith

This method is like `_.intersection` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.intersectionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }]

(static) intersectionWith

This method is like `_.intersection` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order and references of result values are determined by the first array. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.intersectionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }]

(static) invert

Creates an object composed of the inverted keys and values of `object`. If `object` contains duplicate values, subsequent values overwrite property assignments of previous values.
Since:
  • 0.7.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invert(object);
// => { '1': 'c', '2': 'b' }

(static) invert

Creates an object composed of the inverted keys and values of `object`. If `object` contains duplicate values, subsequent values overwrite property assignments of previous values.
Since:
  • 0.7.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invert(object);
// => { '1': 'c', '2': 'b' }

(static) invertBy

This method is like `_.invert` except that the inverted object is generated from the results of running each element of `object` thru `iteratee`. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. The iteratee is invoked with one argument: (value).
Since:
  • 4.1.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }

_.invertBy(object, function(value) {
  return 'group' + value;
});
// => { 'group1': ['a', 'c'], 'group2': ['b'] }

(static) invertBy

This method is like `_.invert` except that the inverted object is generated from the results of running each element of `object` thru `iteratee`. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. The iteratee is invoked with one argument: (value).
Since:
  • 4.1.0
Source:
Example
var object = { 'a': 1, 'b': 2, 'c': 1 };

_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }

_.invertBy(object, function(value) {
  return 'group' + value;
});
// => { 'group1': ['a', 'c'], 'group2': ['b'] }

(static) invoke

Invokes the method at `path` of `object`.
Since:
  • 4.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };

_.invoke(object, 'a[0].b.c.slice', 1, 3);
// => [2, 3]

(static) invoke

Invokes the method at `path` of `object`.
Since:
  • 4.0.0
Source:
Example
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };

_.invoke(object, 'a[0].b.c.slice', 1, 3);
// => [2, 3]

(static) invokeMap

Invokes the method at `path` of each element in `collection`, returning an array of the results of each invoked method. Any additional arguments are provided to each invoked method. If `path` is a function, it's invoked for, and `this` bound to, each element in `collection`.
Since:
  • 4.0.0
Source:
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]

_.invokeMap([123, 456], String.prototype.split, '');
// => [['1', '2', '3'], ['4', '5', '6']]

(static) invokeMap

Invokes the method at `path` of each element in `collection`, returning an array of the results of each invoked method. Any additional arguments are provided to each invoked method. If `path` is a function, it's invoked for, and `this` bound to, each element in `collection`.
Since:
  • 4.0.0
Source:
Example
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// => [[1, 5, 7], [1, 2, 3]]

_.invokeMap([123, 456], String.prototype.split, '');
// => [['1', '2', '3'], ['4', '5', '6']]

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArguments

Checks if `value` is likely an `arguments` object.
Since:
  • 0.1.0
Source:
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray

Checks if `value` is classified as an `Array` object.
Since:
  • 0.1.0
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArray :function

Checks if `value` is classified as an `Array` object.
Type:
  • function
Source:
Example
_.isArray([1, 2, 3]);
// => true

_.isArray(document.body.children);
// => false

_.isArray('abc');
// => false

_.isArray(_.noop);
// => false

(static) isArrayBuffer

Checks if `value` is classified as an `ArrayBuffer` object.
Since:
  • 4.3.0
Source:
Example
_.isArrayBuffer(new ArrayBuffer(2));
// => true

_.isArrayBuffer(new Array(2));
// => false

(static) isArrayBuffer

Checks if `value` is classified as an `ArrayBuffer` object.
Since:
  • 4.3.0
Source:
Example
_.isArrayBuffer(new ArrayBuffer(2));
// => true

_.isArrayBuffer(new Array(2));
// => false

(static) isBuffer

Checks if `value` is a buffer.
Since:
  • 4.3.0
Source:
Example
_.isBuffer(new Buffer(2));
// => true

_.isBuffer(new Uint8Array(2));
// => false

(static) isBuffer

Checks if `value` is a buffer.
Since:
  • 4.3.0
Source:
Example
_.isBuffer(new Buffer(2));
// => true

_.isBuffer(new Uint8Array(2));
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isDate

Checks if `value` is classified as a `Date` object.
Since:
  • 0.1.0
Source:
Example
_.isDate(new Date);
// => true

_.isDate('Mon April 23 2012');
// => false

(static) isMap

Checks if `value` is classified as a `Map` object.
Since:
  • 4.3.0
Source:
Example
_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false

(static) isMap

Checks if `value` is classified as a `Map` object.
Since:
  • 4.3.0
Source:
Example
_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isRegExp

Checks if `value` is classified as a `RegExp` object.
Since:
  • 0.1.0
Source:
Example
_.isRegExp(/abc/);
// => true

_.isRegExp('/abc/');
// => false

(static) isSet

Checks if `value` is classified as a `Set` object.
Since:
  • 4.3.0
Source:
Example
_.isSet(new Set);
// => true

_.isSet(new WeakSet);
// => false

(static) isSet

Checks if `value` is classified as a `Set` object.
Since:
  • 4.3.0
Source:
Example
_.isSet(new Set);
// => true

_.isSet(new WeakSet);
// => false

(static) isTypedArray

Checks if `value` is classified as a typed array.
Since:
  • 3.0.0
Source:
Example
_.isTypedArray(new Uint8Array);
// => true

_.isTypedArray([]);
// => false

(static) isTypedArray

Checks if `value` is classified as a typed array.
Since:
  • 3.0.0
Source:
Example
_.isTypedArray(new Uint8Array);
// => true

_.isTypedArray([]);
// => false

(static) iteratee

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Since:
  • 4.0.0
Source:
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) kebabCase

Converts `string` to [kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).
Since:
  • 3.0.0
Source:
Example
_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'

(static) kebabCase

Converts `string` to [kebab case](https://en.wikipedia.org/wiki/Letter_case#Special_case_styles).
Since:
  • 3.0.0
Source:
Example
_.kebabCase('Foo Bar');
// => 'foo-bar'

_.kebabCase('fooBar');
// => 'foo-bar'

_.kebabCase('__FOO_BAR__');
// => 'foo-bar'

(static) keyBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the last element responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
var array = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

_.keyBy(array, function(o) {
  return String.fromCharCode(o.code);
});
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }

_.keyBy(array, 'dir');
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }

(static) keyBy

Creates an object composed of keys generated from the results of running each element of `collection` thru `iteratee`. The corresponding value of each key is the last element responsible for generating the key. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
var array = [
  { 'dir': 'left', 'code': 97 },
  { 'dir': 'right', 'code': 100 }
];

_.keyBy(array, function(o) {
  return String.fromCharCode(o.code);
});
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }

_.keyBy(array, 'dir');
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }

(static) keys

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Since:
  • 0.1.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keysIn

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Since:
  • 3.0.0
Source:
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) lowerCase

Converts `string`, as space separated words, to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerCase('--Foo-Bar--');
// => 'foo bar'

_.lowerCase('fooBar');
// => 'foo bar'

_.lowerCase('__FOO_BAR__');
// => 'foo bar'

(static) lowerCase

Converts `string`, as space separated words, to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerCase('--Foo-Bar--');
// => 'foo bar'

_.lowerCase('fooBar');
// => 'foo bar'

_.lowerCase('__FOO_BAR__');
// => 'foo bar'

(static) lowerFirst

Converts the first character of `string` to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

(static) lowerFirst

Converts the first character of `string` to lower case.
Since:
  • 4.0.0
Source:
Example
_.lowerFirst('Fred');
// => 'fred'

_.lowerFirst('FRED');
// => 'fRED'

(static) lt

Checks if `value` is less than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lt(1, 3);
// => true

_.lt(3, 3);
// => false

_.lt(3, 1);
// => false

(static) lt

Checks if `value` is less than `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lt(1, 3);
// => true

_.lt(3, 3);
// => false

_.lt(3, 1);
// => false

(static) lte

Checks if `value` is less than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lte(1, 3);
// => true

_.lte(3, 3);
// => true

_.lte(3, 1);
// => false

(static) lte

Checks if `value` is less than or equal to `other`.
Since:
  • 3.9.0
Source:
See:
Example
_.lte(1, 3);
// => true

_.lte(3, 3);
// => true

_.lte(3, 1);
// => false

(static) merge

This method is like `_.assign` except that it recursively merges own and inherited enumerable string keyed properties of source objects into the destination object. Source properties that resolve to `undefined` are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object`.
Since:
  • 0.5.0
Source:
Example
var object = {
  'a': [{ 'b': 2 }, { 'd': 4 }]
};

var other = {
  'a': [{ 'c': 3 }, { 'e': 5 }]
};

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }

(static) merge

This method is like `_.assign` except that it recursively merges own and inherited enumerable string keyed properties of source objects into the destination object. Source properties that resolve to `undefined` are skipped if a destination value exists. Array and plain object properties are merged recursively. Other objects and value types are overridden by assignment. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources. **Note:** This method mutates `object`.
Since:
  • 0.5.0
Source:
Example
var object = {
  'a': [{ 'b': 2 }, { 'd': 4 }]
};

var other = {
  'a': [{ 'c': 3 }, { 'e': 5 }]
};

_.merge(object, other);
// => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }

(static) mergeWith

This method is like `_.merge` except that it accepts `customizer` which is invoked to produce the merged values of the destination and source properties. If `customizer` returns `undefined`, merging is handled by the method instead. The `customizer` is invoked with six arguments: (objValue, srcValue, key, object, source, stack). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
Example
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }

(static) mergeWith

This method is like `_.merge` except that it accepts `customizer` which is invoked to produce the merged values of the destination and source properties. If `customizer` returns `undefined`, merging is handled by the method instead. The `customizer` is invoked with six arguments: (objValue, srcValue, key, object, source, stack). **Note:** This method mutates `object`.
Since:
  • 4.0.0
Source:
Example
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }

(static) method

Creates a function that invokes the method at `path` of a given object. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var objects = [
  { 'a': { 'b': _.constant(2) } },
  { 'a': { 'b': _.constant(1) } }
];

_.map(objects, _.method('a.b'));
// => [2, 1]

_.map(objects, _.method(['a', 'b']));
// => [2, 1]

(static) method

Creates a function that invokes the method at `path` of a given object. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var objects = [
  { 'a': { 'b': _.constant(2) } },
  { 'a': { 'b': _.constant(1) } }
];

_.map(objects, _.method('a.b'));
// => [2, 1]

_.map(objects, _.method(['a', 'b']));
// => [2, 1]

(static) methodOf

The opposite of `_.method`; this method creates a function that invokes the method at a given path of `object`. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var array = _.times(3, _.constant),
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.methodOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// => [2, 0]

(static) methodOf

The opposite of `_.method`; this method creates a function that invokes the method at a given path of `object`. Any additional arguments are provided to the invoked method.
Since:
  • 3.7.0
Source:
Example
var array = _.times(3, _.constant),
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.methodOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// => [2, 0]

(static) multiply

Multiply two numbers.
Since:
  • 4.7.0
Source:
Example
_.multiply(6, 4);
// => 24

(static) multiply

Multiply two numbers.
Since:
  • 4.7.0
Source:
Example
_.multiply(6, 4);
// => 24

(static) next

Gets the next value on a wrapped object following the [iterator protocol](https://mdn.io/iteration_protocols#iterator).
Since:
  • 4.0.0
Source:
Example
var wrapped = _([1, 2]);

wrapped.next();
// => { 'done': false, 'value': 1 }

wrapped.next();
// => { 'done': false, 'value': 2 }

wrapped.next();
// => { 'done': true, 'value': undefined }

(static) next

Gets the next value on a wrapped object following the [iterator protocol](https://mdn.io/iteration_protocols#iterator).
Since:
  • 4.0.0
Source:
Example
var wrapped = _([1, 2]);

wrapped.next();
// => { 'done': false, 'value': 1 }

wrapped.next();
// => { 'done': false, 'value': 2 }

wrapped.next();
// => { 'done': true, 'value': undefined }

(static) now

Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
Since:
  • 2.4.0
Source:
Example
_.defer(function(stamp) {
  console.log(_.now() - stamp);
}, _.now());
// => Logs the number of milliseconds it took for the deferred invocation.

(static) omit

The opposite of `_.pick`; this method creates an object composed of the own and inherited enumerable property paths of `object` that are not omitted. **Note:** This method is considerably slower than `_.pick`.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);
// => { 'b': '2' }

(static) omit

The opposite of `_.pick`; this method creates an object composed of the own and inherited enumerable property paths of `object` that are not omitted. **Note:** This method is considerably slower than `_.pick`.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omit(object, ['a', 'c']);
// => { 'b': '2' }

(static) over

Creates a function that invokes `iteratees` with the arguments it receives and returns their results.
Since:
  • 4.0.0
Source:
Example
var func = _.over([Math.max, Math.min]);

func(1, 2, 3, 4);
// => [4, 1]

(static) over

Creates a function that invokes `iteratees` with the arguments it receives and returns their results.
Since:
  • 4.0.0
Source:
Example
var func = _.over([Math.max, Math.min]);

func(1, 2, 3, 4);
// => [4, 1]

(static) overArgs

Creates a function that invokes `func` with its arguments transformed.
Since:
  • 4.0.0
Source:
Example
function doubled(n) {
  return n * 2;
}

function square(n) {
  return n * n;
}

var func = _.overArgs(function(x, y) {
  return [x, y];
}, [square, doubled]);

func(9, 3);
// => [81, 6]

func(10, 5);
// => [100, 10]

(static) overArgs

Creates a function that invokes `func` with its arguments transformed.
Since:
  • 4.0.0
Source:
Example
function doubled(n) {
  return n * 2;
}

function square(n) {
  return n * n;
}

var func = _.overArgs(function(x, y) {
  return [x, y];
}, [square, doubled]);

func(9, 3);
// => [81, 6]

func(10, 5);
// => [100, 10]

(static) overEvery

Creates a function that checks if **all** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overEvery([Boolean, isFinite]);

func('1');
// => true

func(null);
// => false

func(NaN);
// => false

(static) overEvery

Creates a function that checks if **all** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overEvery([Boolean, isFinite]);

func('1');
// => true

func(null);
// => false

func(NaN);
// => false

(static) overSome

Creates a function that checks if **any** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overSome([Boolean, isFinite]);

func('1');
// => true

func(null);
// => true

func(NaN);
// => false

var matchesFunc = _.overSome([{ 'a': 1 }, { 'a': 2 }])
var matchesPropertyFunc = _.overSome([['a', 1], ['a', 2]])

(static) overSome

Creates a function that checks if **any** of the `predicates` return truthy when invoked with the arguments it receives. Following shorthands are possible for providing predicates. Pass an `Object` and it will be used as an parameter for `_.matches` to create the predicate. Pass an `Array` of parameters for `_.matchesProperty` and the predicate will be created using them.
Since:
  • 4.0.0
Source:
Example
var func = _.overSome([Boolean, isFinite]);

func('1');
// => true

func(null);
// => true

func(NaN);
// => false

var matchesFunc = _.overSome([{ 'a': 1 }, { 'a': 2 }])
var matchesPropertyFunc = _.overSome([['a', 1], ['a', 2]])

(static) partial

Creates a function that invokes `func` with `partials` prepended to the arguments it receives. This method is like `_.bind` except it does **not** alter the `this` binding. The `_.partial.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 0.2.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'

// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'

(static) partial

Creates a function that invokes `func` with `partials` prepended to the arguments it receives. This method is like `_.bind` except it does **not** alter the `this` binding. The `_.partial.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 0.2.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'

// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'

(static) partialRight

This method is like `_.partial` except that partially applied arguments are appended to the arguments it receives. The `_.partialRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 1.0.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'

// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'

(static) partialRight

This method is like `_.partial` except that partially applied arguments are appended to the arguments it receives. The `_.partialRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for partially applied arguments. **Note:** This method doesn't set the "length" property of partially applied functions.
Since:
  • 1.0.0
Source:
Example
function greet(greeting, name) {
  return greeting + ' ' + name;
}

var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'

// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'

(static) partition

Creates an array of elements split into two groups, the first of which contains elements `predicate` returns truthy for, the second of which contains elements `predicate` returns falsey for. The predicate is invoked with one argument: (value).
Since:
  • 3.0.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': false },
  { 'user': 'fred',    'age': 40, 'active': true },
  { 'user': 'pebbles', 'age': 1,  'active': false }
];

_.partition(users, function(o) { return o.active; });
// => objects for [['fred'], ['barney', 'pebbles']]

// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// => objects for [['pebbles'], ['barney', 'fred']]

// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// => objects for [['barney', 'pebbles'], ['fred']]

// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// => objects for [['fred'], ['barney', 'pebbles']]

(static) partition

Creates an array of elements split into two groups, the first of which contains elements `predicate` returns truthy for, the second of which contains elements `predicate` returns falsey for. The predicate is invoked with one argument: (value).
Since:
  • 3.0.0
Source:
Example
var users = [
  { 'user': 'barney',  'age': 36, 'active': false },
  { 'user': 'fred',    'age': 40, 'active': true },
  { 'user': 'pebbles', 'age': 1,  'active': false }
];

_.partition(users, function(o) { return o.active; });
// => objects for [['fred'], ['barney', 'pebbles']]

// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// => objects for [['pebbles'], ['barney', 'fred']]

// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// => objects for [['barney', 'pebbles'], ['fred']]

// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// => objects for [['fred'], ['barney', 'pebbles']]

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) pick

Creates an object composed of the picked `object` properties.
Since:
  • 0.1.0
Source:
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pick(object, ['a', 'c']);
// => { 'a': 1, 'c': 3 }

(static) plant

Creates a clone of the chain sequence planting `value` as the wrapped value.
Since:
  • 3.2.0
Source:
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);

other.value();
// => [9, 16]

wrapped.value();
// => [1, 4]

(static) plant

Creates a clone of the chain sequence planting `value` as the wrapped value.
Since:
  • 3.2.0
Source:
Example
function square(n) {
  return n * n;
}

var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);

other.value();
// => [9, 16]

wrapped.value();
// => [1, 4]

(static) pull

Removes all given values from `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.without`, this method mutates `array`. Use `_.remove` to remove elements from an array by predicate.
Since:
  • 2.0.0
Source:
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pull(array, 'a', 'c');
console.log(array);
// => ['b', 'b']

(static) pull

Removes all given values from `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.without`, this method mutates `array`. Use `_.remove` to remove elements from an array by predicate.
Since:
  • 2.0.0
Source:
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pull(array, 'a', 'c');
console.log(array);
// => ['b', 'b']

(static) pullAt

Removes elements from `array` corresponding to `indexes` and returns an array of removed elements. **Note:** Unlike `_.at`, this method mutates `array`.
Since:
  • 3.0.0
Source:
Example
var array = ['a', 'b', 'c', 'd'];
var pulled = _.pullAt(array, [1, 3]);

console.log(array);
// => ['a', 'c']

console.log(pulled);
// => ['b', 'd']

(static) pullAt

Removes elements from `array` corresponding to `indexes` and returns an array of removed elements. **Note:** Unlike `_.at`, this method mutates `array`.
Since:
  • 3.0.0
Source:
Example
var array = ['a', 'b', 'c', 'd'];
var pulled = _.pullAt(array, [1, 3]);

console.log(array);
// => ['a', 'c']

console.log(pulled);
// => ['b', 'd']

(static) range

Creates an array of numbers (positive and/or negative) progressing from `start` up to, but not including, `end`. A step of `-1` is used if a negative `start` is specified without an `end` or `step`. If `end` is not specified, it's set to `start` with `start` then set to `0`. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Since:
  • 0.1.0
Source:
See:
  • _.inRange, _.rangeRight
Example
_.range(4);
// => [0, 1, 2, 3]

_.range(-4);
// => [0, -1, -2, -3]

_.range(1, 5);
// => [1, 2, 3, 4]

_.range(0, 20, 5);
// => [0, 5, 10, 15]

_.range(0, -4, -1);
// => [0, -1, -2, -3]

_.range(1, 4, 0);
// => [1, 1, 1]

_.range(0);
// => []

(static) range

Creates an array of numbers (positive and/or negative) progressing from `start` up to, but not including, `end`. A step of `-1` is used if a negative `start` is specified without an `end` or `step`. If `end` is not specified, it's set to `start` with `start` then set to `0`. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Since:
  • 0.1.0
Source:
See:
  • _.inRange, _.rangeRight
Example
_.range(4);
// => [0, 1, 2, 3]

_.range(-4);
// => [0, -1, -2, -3]

_.range(1, 5);
// => [1, 2, 3, 4]

_.range(0, 20, 5);
// => [0, 5, 10, 15]

_.range(0, -4, -1);
// => [0, -1, -2, -3]

_.range(1, 4, 0);
// => [1, 1, 1]

_.range(0);
// => []

(static) rangeRight

This method is like `_.range` except that it populates values in descending order.
Since:
  • 4.0.0
Source:
See:
  • _.inRange, _.range
Example
_.rangeRight(4);
// => [3, 2, 1, 0]

_.rangeRight(-4);
// => [-3, -2, -1, 0]

_.rangeRight(1, 5);
// => [4, 3, 2, 1]

_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]

_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]

_.rangeRight(1, 4, 0);
// => [1, 1, 1]

_.rangeRight(0);
// => []

(static) rangeRight

This method is like `_.range` except that it populates values in descending order.
Since:
  • 4.0.0
Source:
See:
  • _.inRange, _.range
Example
_.rangeRight(4);
// => [3, 2, 1, 0]

_.rangeRight(-4);
// => [-3, -2, -1, 0]

_.rangeRight(1, 5);
// => [4, 3, 2, 1]

_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]

_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]

_.rangeRight(1, 4, 0);
// => [1, 1, 1]

_.rangeRight(0);
// => []

(static) rearg

Creates a function that invokes `func` with arguments arranged according to the specified `indexes` where the argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on.
Since:
  • 3.0.0
Source:
Example
var rearged = _.rearg(function(a, b, c) {
  return [a, b, c];
}, [2, 0, 1]);

rearged('b', 'c', 'a')
// => ['a', 'b', 'c']

(static) rearg

Creates a function that invokes `func` with arguments arranged according to the specified `indexes` where the argument value at the first index is provided as the first argument, the argument value at the second index is provided as the second argument, and so on.
Since:
  • 3.0.0
Source:
Example
var rearged = _.rearg(function(a, b, c) {
  return [a, b, c];
}, [2, 0, 1]);

rearged('b', 'c', 'a')
// => ['a', 'b', 'c']

(static) reverse

This method is the wrapper version of `_.reverse`. **Note:** This method mutates the wrapped array.
Since:
  • 0.1.0
Source:
Example
var array = [1, 2, 3];

_(array).reverse().value()
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) reverse

This method is the wrapper version of `_.reverse`. **Note:** This method mutates the wrapped array.
Since:
  • 0.1.0
Source:
Example
var array = [1, 2, 3];

_(array).reverse().value()
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) round

Computes `number` rounded to `precision`.
Since:
  • 3.10.0
Source:
Example
_.round(4.006);
// => 4

_.round(4.006, 2);
// => 4.01

_.round(4060, -2);
// => 4100

(static) round

Computes `number` rounded to `precision`.
Since:
  • 3.10.0
Source:
Example
_.round(4.006);
// => 4

_.round(4.006, 2);
// => 4.01

_.round(4060, -2);
// => 4100

(static) snakeCase

Converts `string` to [snake case](https://en.wikipedia.org/wiki/Snake_case).
Since:
  • 3.0.0
Source:
Example
_.snakeCase('Foo Bar');
// => 'foo_bar'

_.snakeCase('fooBar');
// => 'foo_bar'

_.snakeCase('--FOO-BAR--');
// => 'foo_bar'

(static) snakeCase

Converts `string` to [snake case](https://en.wikipedia.org/wiki/Snake_case).
Since:
  • 3.0.0
Source:
Example
_.snakeCase('Foo Bar');
// => 'foo_bar'

_.snakeCase('fooBar');
// => 'foo_bar'

_.snakeCase('--FOO-BAR--');
// => 'foo_bar'

(static) sortBy

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) sortBy

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Since:
  • 0.1.0
Source:
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) startCase

Converts `string` to [start case](https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage).
Since:
  • 3.1.0
Source:
Example
_.startCase('--foo-bar--');
// => 'Foo Bar'

_.startCase('fooBar');
// => 'Foo Bar'

_.startCase('__FOO_BAR__');
// => 'FOO BAR'

(static) startCase

Converts `string` to [start case](https://en.wikipedia.org/wiki/Letter_case#Stylistic_or_specialised_usage).
Since:
  • 3.1.0
Source:
Example
_.startCase('--foo-bar--');
// => 'Foo Bar'

_.startCase('fooBar');
// => 'Foo Bar'

_.startCase('__FOO_BAR__');
// => 'FOO BAR'

(static) subtract

Subtract two numbers.
Since:
  • 4.0.0
Source:
Example
_.subtract(6, 4);
// => 2

(static) subtract

Subtract two numbers.
Since:
  • 4.0.0
Source:
Example
_.subtract(6, 4);
// => 2

(static) templateSettings :Object

By default, the template delimiters used by lodash are like those in embedded Ruby (ERB) as well as ES2015 template strings. Change the following template settings to use alternative delimiters.
Type:
  • Object
Source:

(static) toInteger

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Since:
  • 4.0.0
Source:
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toNumber

Converts `value` to a number.
Since:
  • 4.0.0
Source:
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) union

Creates an array of unique values, in order, from all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons.
Since:
  • 0.1.0
Source:
Example
_.union([2], [1, 2]);
// => [2, 1]

(static) union

Creates an array of unique values, in order, from all given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons.
Since:
  • 0.1.0
Source:
Example
_.union([2], [1, 2]);
// => [2, 1]

(static) unionBy

This method is like `_.union` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which uniqueness is computed. Result values are chosen from the first array in which the value occurs. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) unionBy

This method is like `_.union` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which uniqueness is computed. Result values are chosen from the first array in which the value occurs. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.unionBy([2.1], [1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) unionWith

This method is like `_.union` except that it accepts `comparator` which is invoked to compare elements of `arrays`. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.unionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) unionWith

This method is like `_.union` except that it accepts `comparator` which is invoked to compare elements of `arrays`. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.unionWith(objects, others, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) upperCase

Converts `string`, as space separated words, to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperCase('--foo-bar');
// => 'FOO BAR'

_.upperCase('fooBar');
// => 'FOO BAR'

_.upperCase('__foo_bar__');
// => 'FOO BAR'

(static) upperCase

Converts `string`, as space separated words, to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperCase('--foo-bar');
// => 'FOO BAR'

_.upperCase('fooBar');
// => 'FOO BAR'

_.upperCase('__foo_bar__');
// => 'FOO BAR'

(static) upperFirst

Converts the first character of `string` to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

(static) upperFirst

Converts the first character of `string` to upper case.
Since:
  • 4.0.0
Source:
Example
_.upperFirst('fred');
// => 'Fred'

_.upperFirst('FRED');
// => 'FRED'

(static) without

Creates an array excluding all given values using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.pull`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2);
// => [3]

(static) without

Creates an array excluding all given values using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. **Note:** Unlike `_.pull`, this method returns a new array.
Since:
  • 0.1.0
Source:
See:
  • _.difference, _.xor
Example
_.without([2, 1, 2, 3], 1, 2);
// => [3]

(static) xor

Creates an array of unique values that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference) of the given arrays. The order of result values is determined by the order they occur in the arrays.
Since:
  • 2.4.0
Source:
See:
  • _.difference, _.without
Example
_.xor([2, 1], [2, 3]);
// => [1, 3]

(static) xor

Creates an array of unique values that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference) of the given arrays. The order of result values is determined by the order they occur in the arrays.
Since:
  • 2.4.0
Source:
See:
  • _.difference, _.without
Example
_.xor([2, 1], [2, 3]);
// => [1, 3]

(static) xorBy

This method is like `_.xor` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which by which they're compared. The order of result values is determined by the order they occur in the arrays. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2, 3.4]

// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) xorBy

This method is like `_.xor` except that it accepts `iteratee` which is invoked for each element of each `arrays` to generate the criterion by which by which they're compared. The order of result values is determined by the order they occur in the arrays. The iteratee is invoked with one argument: (value).
Since:
  • 4.0.0
Source:
Example
_.xorBy([2.1, 1.2], [2.3, 3.4], Math.floor);
// => [1.2, 3.4]

// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 2 }]

(static) xorWith

This method is like `_.xor` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order of result values is determined by the order they occur in the arrays. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.xorWith(objects, others, _.isEqual);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) xorWith

This method is like `_.xor` except that it accepts `comparator` which is invoked to compare elements of `arrays`. The order of result values is determined by the order they occur in the arrays. The comparator is invoked with two arguments: (arrVal, othVal).
Since:
  • 4.0.0
Source:
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.xorWith(objects, others, _.isEqual);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]

(static) zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
Since:
  • 0.1.0
Source:
Example
_.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

(static) zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
Since:
  • 0.1.0
Source:
Example
_.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

(static) zipWith

This method is like `_.zip` except that it accepts `iteratee` to specify how grouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Since:
  • 3.8.0
Source:
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// => [111, 222]

(static) zipWith

This method is like `_.zip` except that it accepts `iteratee` to specify how grouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Since:
  • 3.8.0
Source:
Example
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// => [111, 222]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

value

Executes the chain sequence to resolve the unwrapped value.
Since:
  • 0.1.0
Source:
Example
_([1, 2, 3]).value();
// => [1, 2, 3]

Methods

(static) after(n, func) → {function}

The opposite of `_.before`; this method creates a function that invokes `func` once it's called `n` or more times.
Parameters:
Name Type Description
n number The number of calls before `func` is invoked.
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
  console.log('done saving!');
});

_.forEach(saves, function(type) {
  asyncSave({ 'type': type, 'complete': done });
});
// => Logs 'done saving!' after the two async saves have completed.

(static) after(n, func) → {function}

The opposite of `_.before`; this method creates a function that invokes `func` once it's called `n` or more times.
Parameters:
Name Type Description
n number The number of calls before `func` is invoked.
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
  console.log('done saving!');
});

_.forEach(saves, function(type) {
  asyncSave({ 'type': type, 'complete': done });
});
// => Logs 'done saving!' after the two async saves have completed.

(static) ary(func, nopt) → {function}

Creates a function that invokes `func`, with up to `n` arguments, ignoring any additional arguments.
Parameters:
Name Type Attributes Default Description
func function The function to cap arguments for.
n number <optional>
func.length The arity cap.
Since:
  • 3.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// => [6, 8, 10]

(static) ary(func, nopt) → {function}

Creates a function that invokes `func`, with up to `n` arguments, ignoring any additional arguments.
Parameters:
Name Type Attributes Default Description
func function The function to cap arguments for.
n number <optional>
func.length The arity cap.
Since:
  • 3.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// => [6, 8, 10]

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) before(n, func) → {function}

Creates a function that invokes `func`, with the `this` binding and arguments of the created function, while it's called less than `n` times. Subsequent calls to the created function return the result of the last `func` invocation.
Parameters:
Name Type Description
n number The number of calls at which `func` is no longer invoked.
func function The function to restrict.
Since:
  • 3.0.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
jQuery(element).on('click', _.before(5, addContactToList));
// => Allows adding up to 4 contacts to the list.

(static) capitalize(stringopt) → {string}

Converts the first character of `string` to upper case and the remaining to lower case.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to capitalize.
Since:
  • 3.0.0
Source:
Returns:
Returns the capitalized string.
Type
string
Example
_.capitalize('FRED');
// => 'Fred'

(static) capitalize(stringopt) → {string}

Converts the first character of `string` to upper case and the remaining to lower case.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to capitalize.
Since:
  • 3.0.0
Source:
Returns:
Returns the capitalized string.
Type
string
Example
_.capitalize('FRED');
// => 'Fred'

(static) castArray(value) → {Array}

Casts `value` as an array if it's not one.
Parameters:
Name Type Description
value * The value to inspect.
Since:
  • 4.4.0
Source:
Returns:
Returns the cast array.
Type
Array
Example
_.castArray(1);
// => [1]

_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]

_.castArray('abc');
// => ['abc']

_.castArray(null);
// => [null]

_.castArray(undefined);
// => [undefined]

_.castArray();
// => []

var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

(static) castArray(value) → {Array}

Casts `value` as an array if it's not one.
Parameters:
Name Type Description
value * The value to inspect.
Since:
  • 4.4.0
Source:
Returns:
Returns the cast array.
Type
Array
Example
_.castArray(1);
// => [1]

_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]

_.castArray('abc');
// => ['abc']

_.castArray(null);
// => [null]

_.castArray(undefined);
// => [undefined]

_.castArray();
// => []

var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chain(value) → {Object}

Creates a `lodash` wrapper instance that wraps `value` with explicit method chain sequences enabled. The result of such sequences must be unwrapped with `_#value`.
Parameters:
Name Type Description
value * The value to wrap.
Since:
  • 1.3.0
Source:
Returns:
Returns the new `lodash` wrapper instance.
Type
Object
Example
var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

(static) chunk(array, sizeopt) → {Array}

Creates an array of elements split into groups the length of `size`. If `array` can't be split evenly, the final chunk will be the remaining elements.
Parameters:
Name Type Attributes Default Description
array Array The array to process.
size number <optional>
1 The length of each chunk
Since:
  • 3.0.0
Source:
Returns:
Returns the new array of chunks.
Type
Array
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]

(static) chunk(array, sizeopt) → {Array}

Creates an array of elements split into groups the length of `size`. If `array` can't be split evenly, the final chunk will be the remaining elements.
Parameters:
Name Type Attributes Default Description
array Array The array to process.
size number <optional>
1 The length of each chunk
Since:
  • 3.0.0
Source:
Returns:
Returns the new array of chunks.
Type
Array
Example
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]

(static) clamp(number, loweropt, upper) → {number}

Clamps `number` within the inclusive `lower` and `upper` bounds.
Parameters:
Name Type Attributes Description
number number The number to clamp.
lower number <optional>
The lower bound.
upper number The upper bound.
Since:
  • 4.0.0
Source:
Returns:
Returns the clamped number.
Type
number
Example
_.clamp(-10, -5, 5);
// => -5

_.clamp(10, -5, 5);
// => 5

(static) clamp(number, loweropt, upper) → {number}

Clamps `number` within the inclusive `lower` and `upper` bounds.
Parameters:
Name Type Attributes Description
number number The number to clamp.
lower number <optional>
The lower bound.
upper number The upper bound.
Since:
  • 4.0.0
Source:
Returns:
Returns the clamped number.
Type
number
Example
_.clamp(-10, -5, 5);
// => -5

_.clamp(10, -5, 5);
// => 5

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) clone(value) → {*}

Creates a shallow clone of `value`. **Note:** This method is loosely based on the [structured clone algorithm](https://mdn.io/Structured_clone_algorithm) and supports cloning arrays, array buffers, booleans, date objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. The own enumerable properties of `arguments` objects are cloned as plain objects. An empty object is returned for uncloneable values such as error objects, functions, DOM nodes, and WeakMaps.
Parameters:
Name Type Description
value * The value to clone.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true

(static) cloneDeep(value) → {*}

This method is like `_.clone` except that it recursively clones `value`.
Parameters:
Name Type Description
value * The value to recursively clone.
Since:
  • 1.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false

(static) cloneDeep(value) → {*}

This method is like `_.clone` except that it recursively clones `value`.
Parameters:
Name Type Description
value * The value to recursively clone.
Since:
  • 1.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
var objects = [{ 'a': 1 }, { 'b': 2 }];

var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false

(static) cloneDeepWith(value, customizeropt) → {*}

This method is like `_.cloneWith` except that it recursively clones `value`.
Parameters:
Name Type Attributes Description
value * The value to recursively clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(true);
  }
}

var el = _.cloneDeepWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20

(static) cloneDeepWith(value, customizeropt) → {*}

This method is like `_.cloneWith` except that it recursively clones `value`.
Parameters:
Name Type Attributes Description
value * The value to recursively clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the deep cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(true);
  }
}

var el = _.cloneDeepWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20

(static) cloneWith(value, customizeropt) → {*}

This method is like `_.clone` except that it accepts `customizer` which is invoked to produce the cloned value. If `customizer` returns `undefined`, cloning is handled by the method instead. The `customizer` is invoked with up to four arguments; (value [, index|key, object, stack]).
Parameters:
Name Type Attributes Description
value * The value to clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(false);
  }
}

var el = _.cloneWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0

(static) cloneWith(value, customizeropt) → {*}

This method is like `_.clone` except that it accepts `customizer` which is invoked to produce the cloned value. If `customizer` returns `undefined`, cloning is handled by the method instead. The `customizer` is invoked with up to four arguments; (value [, index|key, object, stack]).
Parameters:
Name Type Attributes Description
value * The value to clone.
customizer function <optional>
The function to customize cloning.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the cloned value.
Type
*
Example
function customizer(value) {
  if (_.isElement(value)) {
    return value.cloneNode(false);
  }
}

var el = _.cloneWith(document.body, customizer);

console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) compact(array) → {Array}

Creates an array with all falsey values removed. The values `false`, `null`, `0`, `""`, `undefined`, and `NaN` are falsey.
Parameters:
Name Type Description
array Array The array to compact.
Since:
  • 0.1.0
Source:
Returns:
Returns the new array of filtered values.
Type
Array
Example
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) concat(array, …valuesopt) → {Array}

Creates a new array concatenating `array` with any additional arrays and/or values.
Parameters:
Name Type Attributes Description
array Array The array to concatenate.
values * <optional>
<repeatable>
The values to concatenate.
Since:
  • 4.0.0
Source:
Returns:
Returns the new concatenated array.
Type
Array
Example
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);

console.log(other);
// => [1, 2, 3, [4]]

console.log(array);
// => [1]

(static) cond(pairs) → {function}

Creates a function that iterates over `pairs` and invokes the corresponding function of the first predicate to return truthy. The predicate-function pairs are invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
pairs Array The predicate-function pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new composite function.
Type
function
Example
var func = _.cond([
  [_.matches({ 'a': 1 }),           _.constant('matches A')],
  [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
  [_.stubTrue,                      _.constant('no match')]
]);

func({ 'a': 1, 'b': 2 });
// => 'matches A'

func({ 'a': 0, 'b': 1 });
// => 'matches B'

func({ 'a': '1', 'b': '2' });
// => 'no match'

(static) cond(pairs) → {function}

Creates a function that iterates over `pairs` and invokes the corresponding function of the first predicate to return truthy. The predicate-function pairs are invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
pairs Array The predicate-function pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new composite function.
Type
function
Example
var func = _.cond([
  [_.matches({ 'a': 1 }),           _.constant('matches A')],
  [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
  [_.stubTrue,                      _.constant('no match')]
]);

func({ 'a': 1, 'b': 2 });
// => 'matches A'

func({ 'a': 0, 'b': 1 });
// => 'matches B'

func({ 'a': '1', 'b': '2' });
// => 'no match'

(static) conforms(source) → {function}

Creates a function that invokes the predicate properties of `source` with the corresponding property values of a given object, returning `true` if all predicates return truthy, else `false`. **Note:** The created function is equivalent to `_.conformsTo` with `source` partially applied.
Parameters:
Name Type Description
source Object The object of property predicates to conform to.
Since:
  • 4.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 2, 'b': 1 },
  { 'a': 1, 'b': 2 }
];

_.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } }));
// => [{ 'a': 1, 'b': 2 }]

(static) conforms(source) → {function}

Creates a function that invokes the predicate properties of `source` with the corresponding property values of a given object, returning `true` if all predicates return truthy, else `false`. **Note:** The created function is equivalent to `_.conformsTo` with `source` partially applied.
Parameters:
Name Type Description
source Object The object of property predicates to conform to.
Since:
  • 4.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 2, 'b': 1 },
  { 'a': 1, 'b': 2 }
];

_.filter(objects, _.conforms({ 'b': function(n) { return n > 1; } }));
// => [{ 'a': 1, 'b': 2 }]

(static) conformsTo(object, source) → {boolean}

Checks if `object` conforms to `source` by invoking the predicate properties of `source` with the corresponding property values of `object`. **Note:** This method is equivalent to `_.conforms` when `source` is partially applied.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property predicates to conform to.
Since:
  • 4.14.0
Source:
Returns:
Returns `true` if `object` conforms, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.conformsTo(object, { 'b': function(n) { return n > 1; } });
// => true

_.conformsTo(object, { 'b': function(n) { return n > 2; } });
// => false

(static) conformsTo(object, source) → {boolean}

Checks if `object` conforms to `source` by invoking the predicate properties of `source` with the corresponding property values of `object`. **Note:** This method is equivalent to `_.conforms` when `source` is partially applied.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property predicates to conform to.
Since:
  • 4.14.0
Source:
Returns:
Returns `true` if `object` conforms, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.conformsTo(object, { 'b': function(n) { return n > 1; } });
// => true

_.conformsTo(object, { 'b': function(n) { return n > 2; } });
// => false

(static) constant(value) → {function}

Creates a function that returns `value`.
Parameters:
Name Type Description
value * The value to return from the new function.
Since:
  • 2.4.0
Source:
Returns:
Returns the new constant function.
Type
function
Example
var objects = _.times(2, _.constant({ 'a': 1 }));

console.log(objects);
// => [{ 'a': 1 }, { 'a': 1 }]

console.log(objects[0] === objects[1]);
// => true

(static) constant(value) → {function}

Creates a function that returns `value`.
Parameters:
Name Type Description
value * The value to return from the new function.
Since:
  • 2.4.0
Source:
Returns:
Returns the new constant function.
Type
function
Example
var objects = _.times(2, _.constant({ 'a': 1 }));

console.log(objects);
// => [{ 'a': 1 }, { 'a': 1 }]

console.log(objects[0] === objects[1]);
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) create(prototype, propertiesopt) → {Object}

Creates an object that inherits from the `prototype` object. If a `properties` object is given, its own enumerable string keyed properties are assigned to the created object.
Parameters:
Name Type Attributes Description
prototype Object The object to inherit from.
properties Object <optional>
The properties to assign to the object.
Since:
  • 2.3.0
Source:
Returns:
Returns the new object.
Type
Object
Example
function Shape() {
  this.x = 0;
  this.y = 0;
}

function Circle() {
  Shape.call(this);
}

Circle.prototype = _.create(Shape.prototype, {
  'constructor': Circle
});

var circle = new Circle;
circle instanceof Circle;
// => true

circle instanceof Shape;
// => true

(static) curry(func, arityopt) → {function}

Creates a function that accepts arguments of `func` and either invokes `func` returning its result, if at least `arity` number of arguments have been provided, or returns a function that accepts the remaining `func` arguments, and so on. The arity of `func` may be specified if `func.length` is not sufficient. The `_.curry.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 2.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curry(abc);

curried(1)(2)(3);
// => [1, 2, 3]

curried(1, 2)(3);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]

(static) curry(func, arityopt) → {function}

Creates a function that accepts arguments of `func` and either invokes `func` returning its result, if at least `arity` number of arguments have been provided, or returns a function that accepts the remaining `func` arguments, and so on. The arity of `func` may be specified if `func.length` is not sufficient. The `_.curry.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 2.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curry(abc);

curried(1)(2)(3);
// => [1, 2, 3]

curried(1, 2)(3);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]

(static) curryRight(func, arityopt) → {function}

This method is like `_.curry` except that arguments are applied to `func` in the manner of `_.partialRight` instead of `_.partial`. The `_.curryRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 3.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curryRight(abc);

curried(3)(2)(1);
// => [1, 2, 3]

curried(2, 3)(1);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]

(static) curryRight(func, arityopt) → {function}

This method is like `_.curry` except that arguments are applied to `func` in the manner of `_.partialRight` instead of `_.partial`. The `_.curryRight.placeholder` value, which defaults to `_` in monolithic builds, may be used as a placeholder for provided arguments. **Note:** This method doesn't set the "length" property of curried functions.
Parameters:
Name Type Attributes Default Description
func function The function to curry.
arity number <optional>
func.length The arity of `func`.
Since:
  • 3.0.0
Source:
Returns:
Returns the new curried function.
Type
function
Example
var abc = function(a, b, c) {
  return [a, b, c];
};

var curried = _.curryRight(abc);

curried(3)(2)(1);
// => [1, 2, 3]

curried(2, 3)(1);
// => [1, 2, 3]

curried(1, 2, 3);
// => [1, 2, 3]

// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]

(static) debounce(func, waitopt, optionsopt) → {function}

Creates a debounced function that delays invoking `func` until after `wait` milliseconds have elapsed since the last time the debounced function was invoked. The debounced function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the debounced function. Subsequent calls to the debounced function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the debounced function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.debounce` and `_.throttle`.
Parameters:
Name Type Attributes Default Description
func function The function to debounce.
wait number <optional>
0 The number of milliseconds to delay.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait number <optional>
The maximum time `func` is allowed to be delayed before it's invoked.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new debounced function.
Type
function
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));

// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));

// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);

// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);

(static) debounce(func, waitopt, optionsopt) → {function}

Creates a debounced function that delays invoking `func` until after `wait` milliseconds have elapsed since the last time the debounced function was invoked. The debounced function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the debounced function. Subsequent calls to the debounced function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the debounced function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.debounce` and `_.throttle`.
Parameters:
Name Type Attributes Default Description
func function The function to debounce.
wait number <optional>
0 The number of milliseconds to delay.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
false Specify invoking on the leading edge of the timeout.
maxWait number <optional>
The maximum time `func` is allowed to be delayed before it's invoked.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new debounced function.
Type
function
Example
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));

// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
  'leading': true,
  'trailing': false
}));

// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);

// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);

(static) deburr(stringopt) → {string}

Deburrs `string` by converting [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table) and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A) letters to basic Latin letters and removing [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to deburr.
Since:
  • 3.0.0
Source:
Returns:
Returns the deburred string.
Type
string
Example
_.deburr('déjà vu');
// => 'deja vu'

(static) deburr(stringopt) → {string}

Deburrs `string` by converting [Latin-1 Supplement](https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)#Character_table) and [Latin Extended-A](https://en.wikipedia.org/wiki/Latin_Extended-A) letters to basic Latin letters and removing [combining diacritical marks](https://en.wikipedia.org/wiki/Combining_Diacritical_Marks).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to deburr.
Since:
  • 3.0.0
Source:
Returns:
Returns the deburred string.
Type
string
Example
_.deburr('déjà vu');
// => 'deja vu'

(static) defaultTo(value, defaultValue) → {*}

Checks `value` to determine whether a default value should be returned in its place. The `defaultValue` is returned if `value` is `NaN`, `null`, or `undefined`.
Parameters:
Name Type Description
value * The value to check.
defaultValue * The default value.
Since:
  • 4.14.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
_.defaultTo(1, 10);
// => 1

_.defaultTo(undefined, 10);
// => 10

(static) defaultTo(value, defaultValue) → {*}

Checks `value` to determine whether a default value should be returned in its place. The `defaultValue` is returned if `value` is `NaN`, `null`, or `undefined`.
Parameters:
Name Type Description
value * The value to check.
defaultValue * The default value.
Since:
  • 4.14.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
_.defaultTo(1, 10);
// => 1

_.defaultTo(undefined, 10);
// => 10

(static) drop(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 0.5.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

_.drop([1, 2, 3], 5);
// => []

_.drop([1, 2, 3], 0);
// => [1, 2, 3]

(static) drop(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 0.5.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

_.drop([1, 2, 3], 5);
// => []

_.drop([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

_.dropRight([1, 2, 3], 5);
// => []

_.dropRight([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements dropped from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to drop.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

_.dropRight([1, 2, 3], 5);
// => []

_.dropRight([1, 2, 3], 0);
// => [1, 2, 3]

(static) dropRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the end. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.dropRightWhile(users, function(o) { return !o.active; });
// => objects for ['barney']

// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['barney', 'fred']

// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// => objects for ['barney']

// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the end. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.dropRightWhile(users, function(o) { return !o.active; });
// => objects for ['barney']

// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['barney', 'fred']

// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// => objects for ['barney']

// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the beginning. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.dropWhile(users, function(o) { return !o.active; });
// => objects for ['pebbles']

// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['fred', 'pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// => objects for ['pebbles']

// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) dropWhile(array, predicateopt) → {Array}

Creates a slice of `array` excluding elements dropped from the beginning. Elements are dropped until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.dropWhile(users, function(o) { return !o.active; });
// => objects for ['pebbles']

// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['fred', 'pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// => objects for ['pebbles']

// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// => objects for ['barney', 'fred', 'pebbles']

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) each(collection, iterateeopt) → {Array|Object}

Iterates over elements of `collection` and invokes `iteratee` for each element. The iteratee is invoked with three arguments: (value, index|key, collection). Iteratee functions may exit iteration early by explicitly returning `false`. **Note:** As with other "Collections" methods, objects with a "length" property are iterated like arrays. To avoid this behavior use `_.forIn` or `_.forOwn` for object iteration.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
  • _.forEachRight
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEach([1, 2], function(value) {
  console.log(value);
});
// => Logs `1` then `2`.

_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) eachRight(collection, iterateeopt) → {Array|Object}

This method is like `_.forEach` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
  • _.forEach
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEachRight([1, 2], function(value) {
  console.log(value);
});
// => Logs `2` then `1`.

(static) eachRight(collection, iterateeopt) → {Array|Object}

This method is like `_.forEach` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
  • _.forEach
Returns:
Returns `collection`.
Type
Array | Object
Example
_.forEachRight([1, 2], function(value) {
  console.log(value);
});
// => Logs `2` then `1`.

(static) endsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` ends with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
string.length The position to search up to.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` ends with `target`, else `false`.
Type
boolean
Example
_.endsWith('abc', 'c');
// => true

_.endsWith('abc', 'b');
// => false

_.endsWith('abc', 'b', 2);
// => true

(static) endsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` ends with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
string.length The position to search up to.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` ends with `target`, else `false`.
Type
boolean
Example
_.endsWith('abc', 'c');
// => true

_.endsWith('abc', 'b');
// => false

_.endsWith('abc', 'b', 2);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) eq(value, other) → {boolean}

Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) comparison between two values to determine if they are equivalent.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.eq(object, object);
// => true

_.eq(object, other);
// => false

_.eq('a', 'a');
// => true

_.eq('a', Object('a'));
// => false

_.eq(NaN, NaN);
// => true

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escape(stringopt) → {string}

Converts the characters "&", "<", ">", '"', and "'" in `string` to their corresponding HTML entities. **Note:** No other characters are escaped. To escape additional characters use a third-party library like [_he_](https://mths.be/he). Though the ">" character is escaped for symmetry, characters like ">" and "/" don't need escaping in HTML and have no special meaning unless they're part of a tag or unquoted attribute value. See [Mathias Bynens's article](https://mathiasbynens.be/notes/ambiguous-ampersands) (under "semi-related fun fact") for more details. When working with HTML you should always [quote attribute values](http://wonko.com/post/html-escaping) to reduce XSS vectors.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 0.1.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escape('fred, barney, & pebbles');
// => 'fred, barney, &amp; pebbles'

(static) escapeRegExp(stringopt) → {string}

Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+", "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 3.0.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'

(static) escapeRegExp(stringopt) → {string}

Escapes the `RegExp` special characters "^", "$", "\", ".", "*", "+", "?", "(", ")", "[", "]", "{", "}", and "|" in `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to escape.
Since:
  • 3.0.0
Source:
Returns:
Returns the escaped string.
Type
string
Example
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) every(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **all** elements of `collection`. Iteration is stopped once `predicate` returns falsey. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** This method returns `true` for [empty collections](https://en.wikipedia.org/wiki/Empty_set) because [everything is true](https://en.wikipedia.org/wiki/Vacuous_truth) of elements of empty collections.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if all elements pass the predicate check, else `false`.
Type
boolean
Example
_.every([true, 1, null, 'yes'], Boolean);
// => false

var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.every(users, 'active');
// => false

(static) fill(array, value, startopt, endopt) → {Array}

Fills elements of `array` with `value` from `start` up to, but not including, `end`. **Note:** This method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to fill.
value * The value to fill `array` with.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.2.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.fill(array, 'a');
console.log(array);
// => ['a', 'a', 'a']

_.fill(Array(3), 2);
// => [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3);
// => [4, '*', '*', 10]

(static) fill(array, value, startopt, endopt) → {Array}

Fills elements of `array` with `value` from `start` up to, but not including, `end`. **Note:** This method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to fill.
value * The value to fill `array` with.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.2.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.fill(array, 'a');
console.log(array);
// => ['a', 'a', 'a']

_.fill(Array(3), 2);
// => [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3);
// => [4, '*', '*', 10]

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) filter(collection, predicateopt) → {Array}

Iterates over elements of `collection`, returning an array of all elements `predicate` returns truthy for. The predicate is invoked with three arguments: (value, index|key, collection). **Note:** Unlike `_.remove`, this method returns a new array.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

_.filter(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// => objects for ['barney']

// Combining several predicates using `_.overEvery` or `_.overSome`.
_.filter(users, _.overSome([{ 'age': 36 }, ['age', 40]]));
// => objects for ['fred', 'barney']

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.find` except that it returns the index of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
0 The index to search from.
Since:
  • 1.1.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.findIndex(users, function(o) { return o.user == 'barney'; });
// => 0

// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// => 1

// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// => 0

// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// => 2

(static) findKey(object, predicateopt) → {string|undefined}

This method is like `_.find` except that it returns the key of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 1.1.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

(static) findKey(object, predicateopt) → {string|undefined}

This method is like `_.find` except that it returns the key of the first element `predicate` returns truthy for instead of the element itself.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 1.1.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findKey(users, function(o) { return o.age < 40; });
// => 'barney' (iteration order is not guaranteed)

// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// => 'pebbles'

// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// => 'barney'

(static) findLastIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.findIndex` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 2.0.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// => 2

// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// => 0

// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// => 2

// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// => 0

(static) findLastIndex(array, predicateopt, fromIndexopt) → {number}

This method is like `_.findIndex` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 2.0.0
Source:
Returns:
Returns the index of the found element, else `-1`.
Type
number
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// => 2

// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// => 0

// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// => 2

// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// => 0

(static) findLastKey(object, predicateopt) → {string|undefined}

This method is like `_.findKey` except that it iterates over elements of a collection in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'

// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'

// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'

(static) findLastKey(object, predicateopt) → {string|undefined}

This method is like `_.findKey` except that it iterates over elements of a collection in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to inspect.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the key of the matched element, else `undefined`.
Type
string | undefined
Example
var users = {
  'barney':  { 'age': 36, 'active': true },
  'fred':    { 'age': 40, 'active': false },
  'pebbles': { 'age': 1,  'active': true }
};

_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'

// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'

// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'

// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) first(array) → {*}

Gets the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the first element of `array`.
Type
*
Example
_.head([1, 2, 3]);
// => 1

_.head([]);
// => undefined

(static) flatMap(collection, iterateeopt) → {Array}

Creates a flattened array of values by running each element in `collection` thru `iteratee` and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [n, n];
}

_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMap(collection, iterateeopt) → {Array}

Creates a flattened array of values by running each element in `collection` thru `iteratee` and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [n, n];
}

_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDeep(collection, iterateeopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDeep([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDeep(collection, iterateeopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDeep([1, 2], duplicate);
// => [1, 1, 2, 2]

(static) flatMapDepth(collection, iterateeopt, depthopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results up to `depth` times.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDepth([1, 2], duplicate, 2);
// => [[1, 1], [2, 2]]

(static) flatMapDepth(collection, iterateeopt, depthopt) → {Array}

This method is like `_.flatMap` except that it recursively flattens the mapped results up to `depth` times.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.7.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
function duplicate(n) {
  return [[[n, n]]];
}

_.flatMapDepth([1, 2], duplicate, 2);
// => [[1, 1], [2, 2]]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flatten(array) → {Array}

Flattens `array` a single level deep.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 0.1.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDeep(array) → {Array}

Recursively flattens `array`.
Parameters:
Name Type Description
array Array The array to flatten.
Since:
  • 3.0.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

(static) flattenDepth(array, depthopt) → {Array}

Recursively flatten `array` up to `depth` times.
Parameters:
Name Type Attributes Default Description
array Array The array to flatten.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.4.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
var array = [1, [2, [3, [4]], 5]];

_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]

_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

(static) flattenDepth(array, depthopt) → {Array}

Recursively flatten `array` up to `depth` times.
Parameters:
Name Type Attributes Default Description
array Array The array to flatten.
depth number <optional>
1 The maximum recursion depth.
Since:
  • 4.4.0
Source:
Returns:
Returns the new flattened array.
Type
Array
Example
var array = [1, [2, [3, [4]], 5]];

_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]

_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

(static) flip(func) → {function}

Creates a function that invokes `func` with arguments reversed.
Parameters:
Name Type Description
func function The function to flip arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flipped function.
Type
function
Example
var flipped = _.flip(function() {
  return _.toArray(arguments);
});

flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']

(static) flip(func) → {function}

Creates a function that invokes `func` with arguments reversed.
Parameters:
Name Type Description
func function The function to flip arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new flipped function.
Type
function
Example
var flipped = _.flip(function() {
  return _.toArray(arguments);
});

flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']

(static) forIn(object, iterateeopt) → {Object}

Iterates over own and inherited enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forIn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).

(static) forIn(object, iterateeopt) → {Object}

Iterates over own and inherited enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forIn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a', 'b', then 'c' (iteration order is not guaranteed).

(static) forInRight(object, iterateeopt) → {Object}

This method is like `_.forIn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forInRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.

(static) forInRight(object, iterateeopt) → {Object}

This method is like `_.forIn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forInRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.

(static) forOwn(object, iterateeopt) → {Object}

Iterates over own enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) forOwn(object, iterateeopt) → {Object}

Iterates over own enumerable string keyed properties of an object and invokes `iteratee` for each property. The iteratee is invoked with three arguments: (value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.3.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwn(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'a' then 'b' (iteration order is not guaranteed).

(static) forOwnRight(object, iterateeopt) → {Object}

This method is like `_.forOwn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwnRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.

(static) forOwnRight(object, iterateeopt) → {Object}

This method is like `_.forOwn` except that it iterates over properties of `object` in the opposite order.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
See:
Returns:
Returns `object`.
Type
Object
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.forOwnRight(new Foo, function(value, key) {
  console.log(key);
});
// => Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.

(static) fromPairs(pairs) → {Object}

The inverse of `_.toPairs`; this method returns an object composed from key-value `pairs`.
Parameters:
Name Type Description
pairs Array The key-value pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

(static) fromPairs(pairs) → {Object}

The inverse of `_.toPairs`; this method returns an object composed from key-value `pairs`.
Parameters:
Name Type Description
pairs Array The key-value pairs.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

(static) functions(object) → {Array}

Creates an array of function property names from own enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functions(new Foo);
// => ['a', 'b']

(static) functions(object) → {Array}

Creates an array of function property names from own enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functions(new Foo);
// => ['a', 'b']

(static) functionsIn(object) → {Array}

Creates an array of function property names from own and inherited enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functionsIn(new Foo);
// => ['a', 'b', 'c']

(static) functionsIn(object) → {Array}

Creates an array of function property names from own and inherited enumerable properties of `object`.
Parameters:
Name Type Description
object Object The object to inspect.
Since:
  • 4.0.0
Source:
See:
Returns:
Returns the function names.
Type
Array
Example
function Foo() {
  this.a = _.constant('a');
  this.b = _.constant('b');
}

Foo.prototype.c = _.constant('c');

_.functionsIn(new Foo);
// => ['a', 'b', 'c']

(static) get(object, path, defaultValueopt) → {*}

Gets the value at `path` of `object`. If the resolved value is `undefined`, the `defaultValue` is returned in its place.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to get.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 3.7.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.get(object, 'a[0].b.c');
// => 3

_.get(object, ['a', '0', 'b', 'c']);
// => 3

_.get(object, 'a.b.c', 'default');
// => 'default'

(static) get(object, path, defaultValueopt) → {*}

Gets the value at `path` of `object`. If the resolved value is `undefined`, the `defaultValue` is returned in its place.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to get.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 3.7.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.get(object, 'a[0].b.c');
// => 3

_.get(object, ['a', '0', 'b', 'c']);
// => 3

_.get(object, 'a.b.c', 'default');
// => 'default'

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) has(object, path) → {boolean}

Checks if `path` is a direct property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });

_.has(object, 'a');
// => true

_.has(object, 'a.b');
// => true

_.has(object, ['a', 'b']);
// => true

_.has(other, 'a');
// => false

(static) hasIn(object, path) → {boolean}

Checks if `path` is a direct or inherited property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) });

_.hasIn(object, 'a');
// => true

_.hasIn(object, 'a.b');
// => true

_.hasIn(object, ['a', 'b']);
// => true

_.hasIn(object, 'b');
// => false

(static) hasIn(object, path) → {boolean}

Checks if `path` is a direct or inherited property of `object`.
Parameters:
Name Type Description
object Object The object to query.
path Array | string The path to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `path` exists, else `false`.
Type
boolean
Example
var object = _.create({ 'a': _.create({ 'b': 2 }) });

_.hasIn(object, 'a');
// => true

_.hasIn(object, 'a.b');
// => true

_.hasIn(object, ['a', 'b']);
// => true

_.hasIn(object, 'b');
// => false

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) identity(value) → {*}

This method returns the first argument it receives.
Parameters:
Name Type Description
value * Any value.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
var object = { 'a': 1 };

console.log(_.identity(object) === object);
// => true

(static) inRange(number, startopt, end) → {boolean}

Checks if `n` is between `start` and up to, but not including, `end`. If `end` is not specified, it's set to `start` with `start` then set to `0`. If `start` is greater than `end` the params are swapped to support negative ranges.
Parameters:
Name Type Attributes Default Description
number number The number to check.
start number <optional>
0 The start of the range.
end number The end of the range.
Since:
  • 3.3.0
Source:
See:
  • _.range, _.rangeRight
Returns:
Returns `true` if `number` is in the range, else `false`.
Type
boolean
Example
_.inRange(3, 2, 4);
// => true

_.inRange(4, 8);
// => true

_.inRange(4, 2);
// => false

_.inRange(2, 2);
// => false

_.inRange(1.2, 2);
// => true

_.inRange(5.2, 4);
// => false

_.inRange(-3, -2, -6);
// => true

(static) inRange(number, startopt, end) → {boolean}

Checks if `n` is between `start` and up to, but not including, `end`. If `end` is not specified, it's set to `start` with `start` then set to `0`. If `start` is greater than `end` the params are swapped to support negative ranges.
Parameters:
Name Type Attributes Default Description
number number The number to check.
start number <optional>
0 The start of the range.
end number The end of the range.
Since:
  • 3.3.0
Source:
See:
  • _.range, _.rangeRight
Returns:
Returns `true` if `number` is in the range, else `false`.
Type
boolean
Example
_.inRange(3, 2, 4);
// => true

_.inRange(4, 8);
// => true

_.inRange(4, 2);
// => false

_.inRange(2, 2);
// => false

_.inRange(1.2, 2);
// => true

_.inRange(5.2, 4);
// => false

_.inRange(-3, -2, -6);
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) includes(collection, value, fromIndexopt) → {boolean}

Checks if `value` is in `collection`. If `collection` is a string, it's checked for a substring of `value`, otherwise [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) is used for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object | string The collection to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is found, else `false`.
Type
boolean
Example
_.includes([1, 2, 3], 1);
// => true

_.includes([1, 2, 3], 1, 2);
// => false

_.includes({ 'a': 1, 'b': 2 }, 1);
// => true

_.includes('abcd', 'bc');
// => true

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) indexOf(array, value, fromIndexopt) → {number}

Gets the index at which the first occurrence of `value` is found in `array` using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons. If `fromIndex` is negative, it's used as the offset from the end of `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
0 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.indexOf([1, 2, 1, 2], 2);
// => 1

// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// => 3

(static) initial(array) → {Array}

Gets all but the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.initial([1, 2, 3]);
// => [1, 2]

(static) initial(array) → {Array}

Gets all but the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.initial([1, 2, 3]);
// => [1, 2]

(static) isArguments(value) → {boolean}

Checks if `value` is likely an `arguments` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an `arguments` object, else `false`.
Type
boolean
Example
_.isArguments(function() { return arguments; }());
// => true

_.isArguments([1, 2, 3]);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLike(value) → {boolean}

Checks if `value` is array-like. A value is considered array-like if it's not a function and has a `value.length` that's an integer greater than or equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is array-like, else `false`.
Type
boolean
Example
_.isArrayLike([1, 2, 3]);
// => true

_.isArrayLike(document.body.children);
// => true

_.isArrayLike('abc');
// => true

_.isArrayLike(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isArrayLikeObject(value) → {boolean}

This method is like `_.isArrayLike` except that it also checks if `value` is an object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an array-like object, else `false`.
Type
boolean
Example
_.isArrayLikeObject([1, 2, 3]);
// => true

_.isArrayLikeObject(document.body.children);
// => true

_.isArrayLikeObject('abc');
// => false

_.isArrayLikeObject(_.noop);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a boolean, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isBoolean(value) → {boolean}

Checks if `value` is classified as a boolean primitive or object.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isBoolean(false);
// => true

_.isBoolean(null);
// => false

(static) isElement(value) → {boolean}

Checks if `value` is likely a DOM element.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a DOM element, else `false`.
Type
boolean
Example
_.isElement(document.body);
// => true

_.isElement('<body>');
// => false

(static) isElement(value) → {boolean}

Checks if `value` is likely a DOM element.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a DOM element, else `false`.
Type
boolean
Example
_.isElement(document.body);
// => true

_.isElement('<body>');
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEmpty(value) → {boolean}

Checks if `value` is an empty object, collection, map, or set. Objects are considered empty if they have no own enumerable string keyed properties. Array-like values such as `arguments` objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a `length` of `0`. Similarly, maps and sets are considered empty if they have a `size` of `0`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is empty, else `false`.
Type
boolean
Example
_.isEmpty(null);
// => true

_.isEmpty(true);
// => true

_.isEmpty(1);
// => true

_.isEmpty([1, 2, 3]);
// => false

_.isEmpty({ 'a': 1 });
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqual(value, other) → {boolean}

Performs a deep comparison between two values to determine if they are equivalent. **Note:** This method supports comparing arrays, array buffers, booleans, date objects, error objects, maps, numbers, `Object` objects, regexes, sets, strings, symbols, and typed arrays. `Object` objects are compared by their own, not inherited, enumerable properties. Functions and DOM nodes are compared by strict equality, i.e. `===`.
Parameters:
Name Type Description
value * The value to compare.
other * The other value to compare.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
var object = { 'a': 1 };
var other = { 'a': 1 };

_.isEqual(object, other);
// => true

object === other;
// => false

(static) isEqualWith(value, other, customizeropt) → {boolean}

This method is like `_.isEqual` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with up to six arguments: (objValue, othValue [, index|key, object, other, stack]).
Parameters:
Name Type Attributes Description
value * The value to compare.
other * The other value to compare.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, othValue) {
  if (isGreeting(objValue) && isGreeting(othValue)) {
    return true;
  }
}

var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];

_.isEqualWith(array, other, customizer);
// => true

(static) isEqualWith(value, other, customizeropt) → {boolean}

This method is like `_.isEqual` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with up to six arguments: (objValue, othValue [, index|key, object, other, stack]).
Parameters:
Name Type Attributes Description
value * The value to compare.
other * The other value to compare.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the values are equivalent, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, othValue) {
  if (isGreeting(objValue) && isGreeting(othValue)) {
    return true;
  }
}

var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];

_.isEqualWith(array, other, customizer);
// => true

(static) isError(value) → {boolean}

Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, or `URIError` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is an error object, else `false`.
Type
boolean
Example
_.isError(new Error);
// => true

_.isError(Error);
// => false

(static) isError(value) → {boolean}

Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, or `URIError` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is an error object, else `false`.
Type
boolean
Example
_.isError(new Error);
// => true

_.isError(Error);
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFinite(value) → {boolean}

Checks if `value` is a finite primitive number. **Note:** This method is based on [`Number.isFinite`](https://mdn.io/Number/isFinite).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a finite number, else `false`.
Type
boolean
Example
_.isFinite(3);
// => true

_.isFinite(Number.MIN_VALUE);
// => true

_.isFinite(Infinity);
// => false

_.isFinite('3');
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isFunction(value) → {boolean}

Checks if `value` is classified as a `Function` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a function, else `false`.
Type
boolean
Example
_.isFunction(_);
// => true

_.isFunction(/abc/);
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isInteger(value) → {boolean}

Checks if `value` is an integer. **Note:** This method is based on [`Number.isInteger`](https://mdn.io/Number/isInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is an integer, else `false`.
Type
boolean
Example
_.isInteger(3);
// => true

_.isInteger(Number.MIN_VALUE);
// => false

_.isInteger(Infinity);
// => false

_.isInteger('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isLength(value) → {boolean}

Checks if `value` is a valid array-like length. **Note:** This method is loosely based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a valid length, else `false`.
Type
boolean
Example
_.isLength(3);
// => true

_.isLength(Number.MIN_VALUE);
// => false

_.isLength(Infinity);
// => false

_.isLength('3');
// => false

(static) isMatch(object, source) → {boolean}

Performs a partial deep comparison between `object` and `source` to determine if `object` contains equivalent property values. **Note:** This method is equivalent to `_.matches` when `source` is partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.isMatch(object, { 'b': 2 });
// => true

_.isMatch(object, { 'b': 1 });
// => false

(static) isMatch(object, source) → {boolean}

Performs a partial deep comparison between `object` and `source` to determine if `object` contains equivalent property values. **Note:** This method is equivalent to `_.matches` when `source` is partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons.
Parameters:
Name Type Description
object Object The object to inspect.
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
var object = { 'a': 1, 'b': 2 };

_.isMatch(object, { 'b': 2 });
// => true

_.isMatch(object, { 'b': 1 });
// => false

(static) isMatchWith(object, source, customizeropt) → {boolean}

This method is like `_.isMatch` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, index|key, object, source).
Parameters:
Name Type Attributes Description
object Object The object to inspect.
source Object The object of property values to match.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, srcValue) {
  if (isGreeting(objValue) && isGreeting(srcValue)) {
    return true;
  }
}

var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };

_.isMatchWith(object, source, customizer);
// => true

(static) isMatchWith(object, source, customizeropt) → {boolean}

This method is like `_.isMatch` except that it accepts `customizer` which is invoked to compare values. If `customizer` returns `undefined`, comparisons are handled by the method instead. The `customizer` is invoked with five arguments: (objValue, srcValue, index|key, object, source).
Parameters:
Name Type Attributes Description
object Object The object to inspect.
source Object The object of property values to match.
customizer function <optional>
The function to customize comparisons.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `object` is a match, else `false`.
Type
boolean
Example
function isGreeting(value) {
  return /^h(?:i|ello)$/.test(value);
}

function customizer(objValue, srcValue) {
  if (isGreeting(objValue) && isGreeting(srcValue)) {
    return true;
  }
}

var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };

_.isMatchWith(object, source, customizer);
// => true

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNaN(value) → {boolean}

Checks if `value` is `NaN`. **Note:** This method is based on [`Number.isNaN`](https://mdn.io/Number/isNaN) and is not the same as global [`isNaN`](https://mdn.io/isNaN) which returns `true` for `undefined` and other non-number values.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `NaN`, else `false`.
Type
boolean
Example
_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false

(static) isNative(value) → {boolean}

Checks if `value` is a pristine native function. **Note:** This method can't reliably detect native functions in the presence of the core-js package because core-js circumvents this kind of detection. Despite multiple requests, the core-js maintainer has made it clear: any attempt to fix the detection will be obstructed. As a result, we're left with little choice but to throw an error. Unfortunately, this also affects packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill), which rely on core-js.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is a native function, else `false`.
Type
boolean
Example
_.isNative(Array.prototype.push);
// => true

_.isNative(_);
// => false

(static) isNative(value) → {boolean}

Checks if `value` is a pristine native function. **Note:** This method can't reliably detect native functions in the presence of the core-js package because core-js circumvents this kind of detection. Despite multiple requests, the core-js maintainer has made it clear: any attempt to fix the detection will be obstructed. As a result, we're left with little choice but to throw an error. Unfortunately, this also affects packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill), which rely on core-js.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `value` is a native function, else `false`.
Type
boolean
Example
_.isNative(Array.prototype.push);
// => true

_.isNative(_);
// => false

(static) isNil(value) → {boolean}

Checks if `value` is `null` or `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is nullish, else `false`.
Type
boolean
Example
_.isNil(null);
// => true

_.isNil(void 0);
// => true

_.isNil(NaN);
// => false

(static) isNil(value) → {boolean}

Checks if `value` is `null` or `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is nullish, else `false`.
Type
boolean
Example
_.isNil(null);
// => true

_.isNil(void 0);
// => true

_.isNil(NaN);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNull(value) → {boolean}

Checks if `value` is `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `null`, else `false`.
Type
boolean
Example
_.isNull(null);
// => true

_.isNull(void 0);
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a number, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isNumber(value) → {boolean}

Checks if `value` is classified as a `Number` primitive or object. **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified as numbers, use the `_.isFinite` method.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isNumber(3);
// => true

_.isNumber(Number.MIN_VALUE);
// => true

_.isNumber(Infinity);
// => true

_.isNumber('3');
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObject(value) → {boolean}

Checks if `value` is the [language type](http://www.ecma-international.org/ecma-262/7.0/#sec-ecmascript-language-types) of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is an object, else `false`.
Type
boolean
Example
_.isObject({});
// => true

_.isObject([1, 2, 3]);
// => true

_.isObject(_.noop);
// => true

_.isObject(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isObjectLike(value) → {boolean}

Checks if `value` is object-like. A value is object-like if it's not `null` and has a `typeof` result of "object".
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is object-like, else `false`.
Type
boolean
Example
_.isObjectLike({});
// => true

_.isObjectLike([1, 2, 3]);
// => true

_.isObjectLike(_.noop);
// => false

_.isObjectLike(null);
// => false

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isPlainObject(value) → {boolean}

Checks if `value` is a plain object, that is, an object created by the `Object` constructor or one with a `[[Prototype]]` of `null`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.8.0
Source:
Returns:
Returns `true` if `value` is a plain object, else `false`.
Type
boolean
Example
function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true

(static) isSafeInteger(value) → {boolean}

Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754 double precision number which isn't the result of a rounded unsafe integer. **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a safe integer, else `false`.
Type
boolean
Example
_.isSafeInteger(3);
// => true

_.isSafeInteger(Number.MIN_VALUE);
// => false

_.isSafeInteger(Infinity);
// => false

_.isSafeInteger('3');
// => false

(static) isSafeInteger(value) → {boolean}

Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754 double precision number which isn't the result of a rounded unsafe integer. **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a safe integer, else `false`.
Type
boolean
Example
_.isSafeInteger(3);
// => true

_.isSafeInteger(Number.MIN_VALUE);
// => false

_.isSafeInteger(Infinity);
// => false

_.isSafeInteger('3');
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is a string, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isString(value) → {boolean}

Checks if `value` is classified as a `String` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Source:
Returns:
Returns `true` if `value` is correctly classified, else `false`.
Type
boolean
Example
_.isString('abc');
// => true

_.isString(1);
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isSymbol(value) → {boolean}

Checks if `value` is classified as a `Symbol` primitive or object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if `value` is a symbol, else `false`.
Type
boolean
Example
_.isSymbol(Symbol.iterator);
// => true

_.isSymbol('abc');
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isUndefined(value) → {boolean}

Checks if `value` is `undefined`.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if `value` is `undefined`, else `false`.
Type
boolean
Example
_.isUndefined(void 0);
// => true

_.isUndefined(null);
// => false

(static) isWeakMap(value) → {boolean}

Checks if `value` is classified as a `WeakMap` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak map, else `false`.
Type
boolean
Example
_.isWeakMap(new WeakMap);
// => true

_.isWeakMap(new Map);
// => false

(static) isWeakMap(value) → {boolean}

Checks if `value` is classified as a `WeakMap` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak map, else `false`.
Type
boolean
Example
_.isWeakMap(new WeakMap);
// => true

_.isWeakMap(new Map);
// => false

(static) isWeakSet(value) → {boolean}

Checks if `value` is classified as a `WeakSet` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak set, else `false`.
Type
boolean
Example
_.isWeakSet(new WeakSet);
// => true

_.isWeakSet(new Set);
// => false

(static) isWeakSet(value) → {boolean}

Checks if `value` is classified as a `WeakSet` object.
Parameters:
Name Type Description
value * The value to check.
Since:
  • 4.3.0
Source:
Returns:
Returns `true` if `value` is a weak set, else `false`.
Type
boolean
Example
_.isWeakSet(new WeakSet);
// => true

_.isWeakSet(new Set);
// => false

(static) iteratee(funcopt) → {function}

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Parameters:
Name Type Attributes Default Description
func * <optional>
_.identity The value to convert to a callback.
Since:
  • 4.0.0
Source:
Returns:
Returns the callback.
Type
function
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) iteratee(funcopt) → {function}

Creates a function that invokes `func` with the arguments of the created function. If `func` is a property name, the created function returns the property value for a given element. If `func` is an array or object, the created function returns `true` for elements that contain the equivalent source properties, otherwise it returns `false`.
Parameters:
Name Type Attributes Default Description
func * <optional>
_.identity The value to convert to a callback.
Since:
  • 4.0.0
Source:
Returns:
Returns the callback.
Type
function
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': true },
  { 'user': 'fred',   'age': 40, 'active': false }
];

// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// => [{ 'user': 'barney', 'age': 36, 'active': true }]

// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// => [{ 'user': 'fred', 'age': 40 }]

// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// => ['barney', 'fred']

// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
  return !_.isRegExp(func) ? iteratee(func) : function(string) {
    return func.test(string);
  };
});

_.filter(['abc', 'def'], /ef/);
// => ['def']

(static) join(array, separatoropt) → {string}

Converts all elements in `array` into a string separated by `separator`.
Parameters:
Name Type Attributes Default Description
array Array The array to convert.
separator string <optional>
',' The element separator.
Since:
  • 4.0.0
Source:
Returns:
Returns the joined string.
Type
string
Example
_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'

(static) join(array, separatoropt) → {string}

Converts all elements in `array` into a string separated by `separator`.
Parameters:
Name Type Attributes Default Description
array Array The array to convert.
separator string <optional>
',' The element separator.
Since:
  • 4.0.0
Source:
Returns:
Returns the joined string.
Type
string
Example
_.join(['a', 'b', 'c'], '~');
// => 'a~b~c'

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keys(object) → {Array}

Creates an array of the own enumerable property names of `object`. **Note:** Non-object values are coerced to objects. See the [ES spec](http://ecma-international.org/ecma-262/7.0/#sec-object.keys) for more details.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)

_.keys('hi');
// => ['0', '1']

(static) keysIn(object) → {Array}

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) keysIn(object) → {Array}

Creates an array of the own and inherited enumerable property names of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property names.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) last(array) → {*}

Gets the last element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the last element of `array`.
Type
*
Example
_.last([1, 2, 3]);
// => 3

(static) lastIndexOf(array, value, fromIndexopt) → {number}

This method is like `_.indexOf` except that it iterates over elements of `array` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// => 3

// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// => 1

(static) lastIndexOf(array, value, fromIndexopt) → {number}

This method is like `_.indexOf` except that it iterates over elements of `array` from right to left.
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
value * The value to search for.
fromIndex number <optional>
array.length-1 The index to search from.
Since:
  • 0.1.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.lastIndexOf([1, 2, 1, 2], 2);
// => 3

// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// => 1

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) map(collection, iterateeopt) → {Array}

Creates an array of values by running each element in `collection` thru `iteratee`. The iteratee is invoked with three arguments: (value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`. The guarded methods are: `ary`, `chunk`, `curry`, `curryRight`, `drop`, `dropRight`, `every`, `fill`, `invert`, `parseInt`, `random`, `range`, `rangeRight`, `repeat`, `sampleSize`, `slice`, `some`, `sortBy`, `split`, `take`, `takeRight`, `template`, `trim`, `trimEnd`, `trimStart`, and `words`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the new mapped array.
Type
Array
Example
function square(n) {
  return n * n;
}

_.map([4, 8], square);
// => [16, 64]

_.map({ 'a': 4, 'b': 8 }, square);
// => [16, 64] (iteration order is not guaranteed)

var users = [
  { 'user': 'barney' },
  { 'user': 'fred' }
];

// The `_.property` iteratee shorthand.
_.map(users, 'user');
// => ['barney', 'fred']

(static) mapKeys(object, iterateeopt) → {Object}

The opposite of `_.mapValues`; this method creates an object with the same values as `object` and keys generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.8.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
  return key + value;
});
// => { 'a1': 1, 'b2': 2 }

(static) mapKeys(object, iterateeopt) → {Object}

The opposite of `_.mapValues`; this method creates an object with the same values as `object` and keys generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.8.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
  return key + value;
});
// => { 'a1': 1, 'b2': 2 }

(static) mapValues(object, iterateeopt) → {Object}

Creates an object with the same keys as `object` and values generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.4.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

(static) mapValues(object, iterateeopt) → {Object}

Creates an object with the same keys as `object` and values generated by running each own enumerable string keyed property of `object` thru `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.4.0
Source:
See:
Returns:
Returns the new mapped object.
Type
Object
Example
var users = {
  'fred':    { 'user': 'fred',    'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
};

_.mapValues(users, function(o) { return o.age; });
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matches(source) → {function}

Creates a function that performs a partial deep comparison between a given object and `source`, returning `true` if the given object has equivalent property values, else `false`. **Note:** The created function is equivalent to `_.isMatch` with `source` partially applied. Partial comparisons will match empty array and empty object `source` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
source Object The object of property values to match.
Since:
  • 3.0.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.filter(objects, _.matches({ 'a': 4, 'c': 6 }));
// => [{ 'a': 4, 'b': 5, 'c': 6 }]

// Checking for several possible values
_.filter(objects, _.overSome([_.matches({ 'a': 1 }), _.matches({ 'a': 4 })]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matchesProperty(path, srcValue) → {function}

Creates a function that performs a partial deep comparison between the value at `path` of a given object to `srcValue`, returning `true` if the object value is equivalent, else `false`. **Note:** Partial comparisons will match empty array and empty object `srcValue` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
path Array | string The path of the property to get.
srcValue * The value to match.
Since:
  • 3.2.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.find(objects, _.matchesProperty('a', 4));
// => { 'a': 4, 'b': 5, 'c': 6 }

// Checking for several possible values
_.filter(objects, _.overSome([_.matchesProperty('a', 1), _.matchesProperty('a', 4)]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) matchesProperty(path, srcValue) → {function}

Creates a function that performs a partial deep comparison between the value at `path` of a given object to `srcValue`, returning `true` if the object value is equivalent, else `false`. **Note:** Partial comparisons will match empty array and empty object `srcValue` values against any array or object value, respectively. See `_.isEqual` for a list of supported value comparisons. **Note:** Multiple values can be checked by combining several matchers using `_.overSome`
Parameters:
Name Type Description
path Array | string The path of the property to get.
srcValue * The value to match.
Since:
  • 3.2.0
Source:
Returns:
Returns the new spec function.
Type
function
Example
var objects = [
  { 'a': 1, 'b': 2, 'c': 3 },
  { 'a': 4, 'b': 5, 'c': 6 }
];

_.find(objects, _.matchesProperty('a', 4));
// => { 'a': 4, 'b': 5, 'c': 6 }

// Checking for several possible values
_.filter(objects, _.overSome([_.matchesProperty('a', 1), _.matchesProperty('a', 4)]));
// => [{ 'a': 1, 'b': 2, 'c': 3 }, { 'a': 4, 'b': 5, 'c': 6 }]

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) max(array) → {*}

Computes the maximum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
_.max([4, 2, 8, 6]);
// => 8

_.max([]);
// => undefined

(static) maxBy(array, iterateeopt) → {*}

This method is like `_.max` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.maxBy(objects, function(o) { return o.n; });
// => { 'n': 2 }

// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// => { 'n': 2 }

(static) maxBy(array, iterateeopt) → {*}

This method is like `_.max` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the maximum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.maxBy(objects, function(o) { return o.n; });
// => { 'n': 2 }

// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// => { 'n': 2 }

(static) mean(array) → {number}

Computes the mean of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 4.0.0
Source:
Returns:
Returns the mean.
Type
number
Example
_.mean([4, 2, 8, 6]);
// => 5

(static) mean(array) → {number}

Computes the mean of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 4.0.0
Source:
Returns:
Returns the mean.
Type
number
Example
_.mean([4, 2, 8, 6]);
// => 5

(static) meanBy(array, iterateeopt) → {number}

This method is like `_.mean` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be averaged. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.7.0
Source:
Returns:
Returns the mean.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.meanBy(objects, function(o) { return o.n; });
// => 5

// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// => 5

(static) meanBy(array, iterateeopt) → {number}

This method is like `_.mean` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be averaged. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.7.0
Source:
Returns:
Returns the mean.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.meanBy(objects, function(o) { return o.n; });
// => 5

// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// => 5

(static) memoize(func, resolveropt) → {function}

Creates a function that memoizes the result of `func`. If `resolver` is provided, it determines the cache key for storing the result based on the arguments provided to the memoized function. By default, the first argument provided to the memoized function is used as the map cache key. The `func` is invoked with the `this` binding of the memoized function. **Note:** The cache is exposed as the `cache` property on the memoized function. Its creation may be customized by replacing the `_.memoize.Cache` constructor with one whose instances implement the [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) method interface of `clear`, `delete`, `get`, `has`, and `set`.
Parameters:
Name Type Attributes Description
func function The function to have its output memoized.
resolver function <optional>
The function to resolve the cache key.
Since:
  • 0.1.0
Source:
Returns:
Returns the new memoized function.
Type
function
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };

var values = _.memoize(_.values);
values(object);
// => [1, 2]

values(other);
// => [3, 4]

object.a = 2;
values(object);
// => [1, 2]

// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']

// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;

(static) memoize(func, resolveropt) → {function}

Creates a function that memoizes the result of `func`. If `resolver` is provided, it determines the cache key for storing the result based on the arguments provided to the memoized function. By default, the first argument provided to the memoized function is used as the map cache key. The `func` is invoked with the `this` binding of the memoized function. **Note:** The cache is exposed as the `cache` property on the memoized function. Its creation may be customized by replacing the `_.memoize.Cache` constructor with one whose instances implement the [`Map`](http://ecma-international.org/ecma-262/7.0/#sec-properties-of-the-map-prototype-object) method interface of `clear`, `delete`, `get`, `has`, and `set`.
Parameters:
Name Type Attributes Description
func function The function to have its output memoized.
resolver function <optional>
The function to resolve the cache key.
Since:
  • 0.1.0
Source:
Returns:
Returns the new memoized function.
Type
function
Example
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };

var values = _.memoize(_.values);
values(object);
// => [1, 2]

values(other);
// => [3, 4]

object.a = 2;
values(object);
// => [1, 2]

// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']

// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) min(array) → {*}

Computes the minimum value of `array`. If `array` is empty or falsey, `undefined` is returned.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 0.1.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
_.min([4, 2, 8, 6]);
// => 2

_.min([]);
// => undefined

(static) minBy(array, iterateeopt) → {*}

This method is like `_.min` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }

// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

(static) minBy(array, iterateeopt) → {*}

This method is like `_.min` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which the value is ranked. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the minimum value.
Type
*
Example
var objects = [{ 'n': 1 }, { 'n': 2 }];

_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }

// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) mixin(objectopt, source, optionsopt) → {function|Object}

Adds all own enumerable string keyed function properties of a source object to the destination object. If `object` is a function, then methods are added to its prototype as well. **Note:** Use `_.runInContext` to create a pristine `lodash` function to avoid conflicts caused by modifying the original.
Parameters:
Name Type Attributes Default Description
object function | Object <optional>
lodash The destination object.
source Object The object of functions to add.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
chain boolean <optional>
true Specify whether mixins are chainable.
Since:
  • 0.1.0
Source:
Returns:
Returns `object`.
Type
function | Object
Example
function vowels(string) {
  return _.filter(string, function(v) {
    return /[aeiou]/i.test(v);
  });
}

_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']

_('fred').vowels().value();
// => ['e']

_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// => ['e']

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) negate(predicate) → {function}

Creates a function that negates the result of the predicate `func`. The `func` predicate is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
predicate function The predicate to negate.
Since:
  • 3.0.0
Source:
Returns:
Returns the new negated function.
Type
function
Example
function isEven(n) {
  return n % 2 == 0;
}

_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// => [1, 3, 5]

(static) noConflict() → {function}

Reverts the `_` variable to its previous value and returns a reference to the `lodash` function.
Since:
  • 0.1.0
Source:
Returns:
Returns the `lodash` function.
Type
function
Example
var lodash = _.noConflict();

(static) noConflict() → {function}

Reverts the `_` variable to its previous value and returns a reference to the `lodash` function.
Since:
  • 0.1.0
Source:
Returns:
Returns the `lodash` function.
Type
function
Example
var lodash = _.noConflict();

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) noop()

This method returns `undefined`.
Since:
  • 2.3.0
Source:
Example
_.times(2, _.noop);
// => [undefined, undefined]

(static) now() → {number}

Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
Since:
  • 2.4.0
Source:
Returns:
Returns the timestamp.
Type
number
Example
_.defer(function(stamp) {
  console.log(_.now() - stamp);
}, _.now());
// => Logs the number of milliseconds it took for the deferred invocation.

(static) nth(array, nopt) → {*}

Gets the element at index `n` of `array`. If `n` is negative, the nth element from the end is returned.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
0 The index of the element to return.
Since:
  • 4.11.0
Source:
Returns:
Returns the nth element of `array`.
Type
*
Example
var array = ['a', 'b', 'c', 'd'];

_.nth(array, 1);
// => 'b'

_.nth(array, -2);
// => 'c';

(static) nth(array, nopt) → {*}

Gets the element at index `n` of `array`. If `n` is negative, the nth element from the end is returned.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
0 The index of the element to return.
Since:
  • 4.11.0
Source:
Returns:
Returns the nth element of `array`.
Type
*
Example
var array = ['a', 'b', 'c', 'd'];

_.nth(array, 1);
// => 'b'

_.nth(array, -2);
// => 'c';

(static) nthArg(nopt) → {function}

Creates a function that gets the argument at index `n`. If `n` is negative, the nth argument from the end is returned.
Parameters:
Name Type Attributes Default Description
n number <optional>
0 The index of the argument to return.
Since:
  • 4.0.0
Source:
Returns:
Returns the new pass-thru function.
Type
function
Example
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// => 'b'

var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// => 'c'

(static) nthArg(nopt) → {function}

Creates a function that gets the argument at index `n`. If `n` is negative, the nth argument from the end is returned.
Parameters:
Name Type Attributes Default Description
n number <optional>
0 The index of the argument to return.
Since:
  • 4.0.0
Source:
Returns:
Returns the new pass-thru function.
Type
function
Example
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// => 'b'

var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// => 'c'

(static) omitBy(object, predicateopt) → {Object}

The opposite of `_.pickBy`; this method creates an object composed of the own and inherited enumerable string keyed properties of `object` that `predicate` doesn't return truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omitBy(object, _.isNumber);
// => { 'b': '2' }

(static) omitBy(object, predicateopt) → {Object}

The opposite of `_.pickBy`; this method creates an object composed of the own and inherited enumerable string keyed properties of `object` that `predicate` doesn't return truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.omitBy(object, _.isNumber);
// => { 'b': '2' }

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) once(func) → {function}

Creates a function that is restricted to invoking `func` once. Repeat calls to the function return the value of the first invocation. The `func` is invoked with the `this` binding and arguments of the created function.
Parameters:
Name Type Description
func function The function to restrict.
Since:
  • 0.1.0
Source:
Returns:
Returns the new restricted function.
Type
function
Example
var initialize = _.once(createApplication);
initialize();
initialize();
// => `createApplication` is invoked once

(static) orderBy(collection, iterateesopt, ordersopt) → {Array}

This method is like `_.sortBy` except that it allows specifying the sort orders of the iteratees to sort by. If `orders` is unspecified, all values are sorted in ascending order. Otherwise, specify an order of "desc" for descending or "asc" for ascending sort order of corresponding values.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees Array:.<Array:> | Array:.<function()> | Array:.<Object:> | Array:.<string:> <optional>
[_.identity] The iteratees to sort by.
orders Array:.<string:> <optional>
The sort orders of `iteratees`.
Since:
  • 4.0.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 34 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 36 }
];

// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

(static) orderBy(collection, iterateesopt, ordersopt) → {Array}

This method is like `_.sortBy` except that it allows specifying the sort orders of the iteratees to sort by. If `orders` is unspecified, all values are sorted in ascending order. Otherwise, specify an order of "desc" for descending or "asc" for ascending sort order of corresponding values.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees Array:.<Array:> | Array:.<function()> | Array:.<Object:> | Array:.<string:> <optional>
[_.identity] The iteratees to sort by.
orders Array:.<string:> <optional>
The sort orders of `iteratees`.
Since:
  • 4.0.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 34 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 36 }
];

// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]

(static) pad(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left and right sides if it's shorter than `length`. Padding characters are truncated if they can't be evenly divided by `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 3.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.pad('abc', 8);
// => '  abc   '

_.pad('abc', 8, '_-');
// => '_-abc_-_'

_.pad('abc', 3);
// => 'abc'

(static) pad(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left and right sides if it's shorter than `length`. Padding characters are truncated if they can't be evenly divided by `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 3.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.pad('abc', 8);
// => '  abc   '

_.pad('abc', 8, '_-');
// => '_-abc_-_'

_.pad('abc', 3);
// => 'abc'

(static) padEnd(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the right side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padEnd('abc', 6);
// => 'abc   '

_.padEnd('abc', 6, '_-');
// => 'abc_-_'

_.padEnd('abc', 3);
// => 'abc'

(static) padEnd(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the right side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padEnd('abc', 6);
// => 'abc   '

_.padEnd('abc', 6, '_-');
// => 'abc_-_'

_.padEnd('abc', 3);
// => 'abc'

(static) padStart(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padStart('abc', 6);
// => '   abc'

_.padStart('abc', 6, '_-');
// => '_-_abc'

_.padStart('abc', 3);
// => 'abc'

(static) padStart(stringopt, lengthopt, charsopt) → {string}

Pads `string` on the left side if it's shorter than `length`. Padding characters are truncated if they exceed `length`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to pad.
length number <optional>
0 The padding length.
chars string <optional>
' ' The string used as padding.
Since:
  • 4.0.0
Source:
Returns:
Returns the padded string.
Type
string
Example
_.padStart('abc', 6);
// => '   abc'

_.padStart('abc', 6, '_-');
// => '_-_abc'

_.padStart('abc', 3);
// => 'abc'

(static) parseInt(string, radixopt) → {number}

Converts `string` to an integer of the specified radix. If `radix` is `undefined` or `0`, a `radix` of `10` is used unless `value` is a hexadecimal, in which case a `radix` of `16` is used. **Note:** This method aligns with the [ES5 implementation](https://es5.github.io/#x15.1.2.2) of `parseInt`.
Parameters:
Name Type Attributes Default Description
string string The string to convert.
radix number <optional>
10 The radix to interpret `value` by.
Since:
  • 1.1.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.parseInt('08');
// => 8

_.map(['6', '08', '10'], _.parseInt);
// => [6, 8, 10]

(static) parseInt(string, radixopt) → {number}

Converts `string` to an integer of the specified radix. If `radix` is `undefined` or `0`, a `radix` of `10` is used unless `value` is a hexadecimal, in which case a `radix` of `16` is used. **Note:** This method aligns with the [ES5 implementation](https://es5.github.io/#x15.1.2.2) of `parseInt`.
Parameters:
Name Type Attributes Default Description
string string The string to convert.
radix number <optional>
10 The radix to interpret `value` by.
Since:
  • 1.1.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.parseInt('08');
// => 8

_.map(['6', '08', '10'], _.parseInt);
// => [6, 8, 10]

(static) pickBy(object, predicateopt) → {Object}

Creates an object composed of the `object` properties `predicate` returns truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

(static) pickBy(object, predicateopt) → {Object}

Creates an object composed of the `object` properties `predicate` returns truthy for. The predicate is invoked with two arguments: (value, key).
Parameters:
Name Type Attributes Default Description
object Object The source object.
predicate function <optional>
_.identity The function invoked per property.
Since:
  • 4.0.0
Source:
Returns:
Returns the new object.
Type
Object
Example
var object = { 'a': 1, 'b': '2', 'c': 3 };

_.pickBy(object, _.isNumber);
// => { 'a': 1, 'c': 3 }

(static) property(path) → {function}

Creates a function that returns the value at `path` of a given object.
Parameters:
Name Type Description
path Array | string The path of the property to get.
Since:
  • 2.4.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];

_.map(objects, _.property('a.b'));
// => [2, 1]

_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// => [1, 2]

(static) property(path) → {function}

Creates a function that returns the value at `path` of a given object.
Parameters:
Name Type Description
path Array | string The path of the property to get.
Since:
  • 2.4.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];

_.map(objects, _.property('a.b'));
// => [2, 1]

_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// => [1, 2]

(static) propertyOf(object) → {function}

The opposite of `_.property`; this method creates a function that returns the value at a given path of `object`.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var array = [0, 1, 2],
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// => [2, 0]

(static) propertyOf(object) → {function}

The opposite of `_.property`; this method creates a function that returns the value at a given path of `object`.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the new accessor function.
Type
function
Example
var array = [0, 1, 2],
    object = { 'a': array, 'b': array, 'c': array };

_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// => [2, 0]

_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// => [2, 0]

(static) pullAll(array, values) → {Array}

This method is like `_.pull` except that it accepts an array of values to remove. **Note:** Unlike `_.difference`, this method mutates `array`.
Parameters:
Name Type Description
array Array The array to modify.
values Array The values to remove.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pullAll(array, ['a', 'c']);
console.log(array);
// => ['b', 'b']

(static) pullAll(array, values) → {Array}

This method is like `_.pull` except that it accepts an array of values to remove. **Note:** Unlike `_.difference`, this method mutates `array`.
Parameters:
Name Type Description
array Array The array to modify.
values Array The values to remove.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = ['a', 'b', 'c', 'a', 'b', 'c'];

_.pullAll(array, ['a', 'c']);
console.log(array);
// => ['b', 'b']

(static) pullAllBy(array, values, iterateeopt) → {Array}

This method is like `_.pullAll` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.differenceBy`, this method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
values Array The values to remove.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];

_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// => [{ 'x': 2 }]

(static) pullAllBy(array, values, iterateeopt) → {Array}

This method is like `_.pullAll` except that it accepts `iteratee` which is invoked for each element of `array` and `values` to generate the criterion by which they're compared. The iteratee is invoked with one argument: (value). **Note:** Unlike `_.differenceBy`, this method mutates `array`.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
values Array The values to remove.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];

_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// => [{ 'x': 2 }]

(static) pullAllWith(array, values, comparatoropt) → {Array}

This method is like `_.pullAll` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.differenceWith`, this method mutates `array`.
Parameters:
Name Type Attributes Description
array Array The array to modify.
values Array The values to remove.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.6.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];

_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]

(static) pullAllWith(array, values, comparatoropt) → {Array}

This method is like `_.pullAll` except that it accepts `comparator` which is invoked to compare elements of `array` to `values`. The comparator is invoked with two arguments: (arrVal, othVal). **Note:** Unlike `_.differenceWith`, this method mutates `array`.
Parameters:
Name Type Attributes Description
array Array The array to modify.
values Array The values to remove.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.6.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];

_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// => [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]

(static) random(loweropt, upperopt, floatingopt) → {number}

Produces a random number between the inclusive `lower` and `upper` bounds. If only one argument is provided a number between `0` and the given number is returned. If `floating` is `true`, or either `lower` or `upper` are floats, a floating-point number is returned instead of an integer. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Parameters:
Name Type Attributes Default Description
lower number <optional>
0 The lower bound.
upper number <optional>
1 The upper bound.
floating boolean <optional>
Specify returning a floating-point number.
Since:
  • 0.7.0
Source:
Returns:
Returns the random number.
Type
number
Example
_.random(0, 5);
// => an integer between 0 and 5

_.random(5);
// => also an integer between 0 and 5

_.random(5, true);
// => a floating-point number between 0 and 5

_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2

(static) random(loweropt, upperopt, floatingopt) → {number}

Produces a random number between the inclusive `lower` and `upper` bounds. If only one argument is provided a number between `0` and the given number is returned. If `floating` is `true`, or either `lower` or `upper` are floats, a floating-point number is returned instead of an integer. **Note:** JavaScript follows the IEEE-754 standard for resolving floating-point values which can produce unexpected results.
Parameters:
Name Type Attributes Default Description
lower number <optional>
0 The lower bound.
upper number <optional>
1 The upper bound.
floating boolean <optional>
Specify returning a floating-point number.
Since:
  • 0.7.0
Source:
Returns:
Returns the random number.
Type
number
Example
_.random(0, 5);
// => an integer between 0 and 5

_.random(5);
// => also an integer between 0 and 5

_.random(5, true);
// => a floating-point number between 0 and 5

_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduce(collection, iterateeopt, accumulatoropt) → {*}

Reduces `collection` to a value which is the accumulated result of running each element in `collection` thru `iteratee`, where each successive invocation is supplied the return value of the previous. If `accumulator` is not given, the first element of `collection` is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection). Many lodash methods are guarded to work as iteratees for methods like `_.reduce`, `_.reduceRight`, and `_.transform`. The guarded methods are: `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`, and `sortBy`
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
_.reduce([1, 2], function(sum, n) {
  return sum + n;
}, 0);
// => 3

_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
  return result;
}, {});
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)

(static) reduceRight(collection, iterateeopt, accumulatoropt) → {*}

This method is like `_.reduce` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
var array = [[0, 1], [2, 3], [4, 5]];

_.reduceRight(array, function(flattened, other) {
  return flattened.concat(other);
}, []);
// => [4, 5, 2, 3, 0, 1]

(static) reduceRight(collection, iterateeopt, accumulatoropt) → {*}

This method is like `_.reduce` except that it iterates over elements of `collection` from right to left.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The initial value.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the accumulated value.
Type
*
Example
var array = [[0, 1], [2, 3], [4, 5]];

_.reduceRight(array, function(flattened, other) {
  return flattened.concat(other);
}, []);
// => [4, 5, 2, 3, 0, 1]

(static) reject(collection, predicateopt) → {Array}

The opposite of `_.filter`; this method returns the elements of `collection` that `predicate` does **not** return truthy for.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': true }
];

_.reject(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// => objects for ['barney']

(static) reject(collection, predicateopt) → {Array}

The opposite of `_.filter`; this method returns the elements of `collection` that `predicate` does **not** return truthy for.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
See:
Returns:
Returns the new filtered array.
Type
Array
Example
var users = [
  { 'user': 'barney', 'age': 36, 'active': false },
  { 'user': 'fred',   'age': 40, 'active': true }
];

_.reject(users, function(o) { return !o.active; });
// => objects for ['fred']

// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// => objects for ['fred']

// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// => objects for ['barney']

(static) remove(array, predicateopt) → {Array}

Removes all elements from `array` that `predicate` returns truthy for and returns an array of the removed elements. The predicate is invoked with three arguments: (value, index, array). **Note:** Unlike `_.filter`, this method mutates `array`. Use `_.pull` to pull elements from an array by value.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the new array of removed elements.
Type
Array
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

(static) remove(array, predicateopt) → {Array}

Removes all elements from `array` that `predicate` returns truthy for and returns an array of the removed elements. The predicate is invoked with three arguments: (value, index, array). **Note:** Unlike `_.filter`, this method mutates `array`. Use `_.pull` to pull elements from an array by value.
Parameters:
Name Type Attributes Default Description
array Array The array to modify.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 2.0.0
Source:
Returns:
Returns the new array of removed elements.
Type
Array
Example
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

(static) repeat(stringopt, nopt) → {string}

Repeats the given string `n` times.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to repeat.
n number <optional>
1 The number of times to repeat the string.
Since:
  • 3.0.0
Source:
Returns:
Returns the repeated string.
Type
string
Example
_.repeat('*', 3);
// => '***'

_.repeat('abc', 2);
// => 'abcabc'

_.repeat('abc', 0);
// => ''

(static) repeat(stringopt, nopt) → {string}

Repeats the given string `n` times.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to repeat.
n number <optional>
1 The number of times to repeat the string.
Since:
  • 3.0.0
Source:
Returns:
Returns the repeated string.
Type
string
Example
_.repeat('*', 3);
// => '***'

_.repeat('abc', 2);
// => 'abcabc'

_.repeat('abc', 0);
// => ''

(static) replace(stringopt, pattern, replacement) → {string}

Replaces matches for `pattern` in `string` with `replacement`. **Note:** This method is based on [`String#replace`](https://mdn.io/String/replace).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to modify.
pattern RegExp | string The pattern to replace.
replacement function | string The match replacement.
Since:
  • 4.0.0
Source:
Returns:
Returns the modified string.
Type
string
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// => 'Hi Barney'

(static) replace(stringopt, pattern, replacement) → {string}

Replaces matches for `pattern` in `string` with `replacement`. **Note:** This method is based on [`String#replace`](https://mdn.io/String/replace).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to modify.
pattern RegExp | string The pattern to replace.
replacement function | string The match replacement.
Since:
  • 4.0.0
Source:
Returns:
Returns the modified string.
Type
string
Example
_.replace('Hi Fred', 'Fred', 'Barney');
// => 'Hi Barney'

(static) rest(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the created function and arguments from `start` and beyond provided as an array. **Note:** This method is based on the [rest parameter](https://mdn.io/rest_parameters).
Parameters:
Name Type Attributes Default Description
func function The function to apply a rest parameter to.
start number <optional>
func.length-1 The start position of the rest parameter.
Since:
  • 4.0.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.rest(function(what, names) {
  return what + ' ' + _.initial(names).join(', ') +
    (_.size(names) > 1 ? ', & ' : '') + _.last(names);
});

say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'

(static) rest(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the created function and arguments from `start` and beyond provided as an array. **Note:** This method is based on the [rest parameter](https://mdn.io/rest_parameters).
Parameters:
Name Type Attributes Default Description
func function The function to apply a rest parameter to.
start number <optional>
func.length-1 The start position of the rest parameter.
Since:
  • 4.0.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.rest(function(what, names) {
  return what + ' ' + _.initial(names).join(', ') +
    (_.size(names) > 1 ? ', & ' : '') + _.last(names);
});

say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) result(object, path, defaultValueopt) → {*}

This method is like `_.get` except that if the resolved value is a function it's invoked with the `this` binding of its parent object and its result is returned.
Parameters:
Name Type Attributes Description
object Object The object to query.
path Array | string The path of the property to resolve.
defaultValue * <optional>
The value returned for `undefined` resolved values.
Since:
  • 0.1.0
Source:
Returns:
Returns the resolved value.
Type
*
Example
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };

_.result(object, 'a[0].b.c1');
// => 3

_.result(object, 'a[0].b.c2');
// => 4

_.result(object, 'a[0].b.c3', 'default');
// => 'default'

_.result(object, 'a[0].b.c3', _.constant('default'));
// => 'default'

(static) reverse(array) → {Array}

Reverses `array` so that the first element becomes the last, the second element becomes the second to last, and so on. **Note:** This method mutates `array` and is based on [`Array#reverse`](https://mdn.io/Array/reverse).
Parameters:
Name Type Description
array Array The array to modify.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) reverse(array) → {Array}

Reverses `array` so that the first element becomes the last, the second element becomes the second to last, and so on. **Note:** This method mutates `array` and is based on [`Array#reverse`](https://mdn.io/Array/reverse).
Parameters:
Name Type Description
array Array The array to modify.
Since:
  • 4.0.0
Source:
Returns:
Returns `array`.
Type
Array
Example
var array = [1, 2, 3];

_.reverse(array);
// => [3, 2, 1]

console.log(array);
// => [3, 2, 1]

(static) runInContext(contextopt) → {function}

Create a new pristine `lodash` function using the `context` object.
Parameters:
Name Type Attributes Default Description
context Object <optional>
root The context object.
Since:
  • 1.1.0
Source:
Returns:
Returns a new `lodash` function.
Type
function
Example
_.mixin({ 'foo': _.constant('foo') });

var lodash = _.runInContext();
lodash.mixin({ 'bar': lodash.constant('bar') });

_.isFunction(_.foo);
// => true
_.isFunction(_.bar);
// => false

lodash.isFunction(lodash.foo);
// => false
lodash.isFunction(lodash.bar);
// => true

// Create a suped-up `defer` in Node.js.
var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;

(static) sample(collection) → {*}

Gets a random element from `collection`.
Parameters:
Name Type Description
collection Array | Object The collection to sample.
Since:
  • 2.0.0
Source:
Returns:
Returns the random element.
Type
*
Example
_.sample([1, 2, 3, 4]);
// => 2

(static) sample(collection) → {*}

Gets a random element from `collection`.
Parameters:
Name Type Description
collection Array | Object The collection to sample.
Since:
  • 2.0.0
Source:
Returns:
Returns the random element.
Type
*
Example
_.sample([1, 2, 3, 4]);
// => 2

(static) sampleSize(collection, nopt) → {Array}

Gets `n` random elements at unique keys from `collection` up to the size of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to sample.
n number <optional>
1 The number of elements to sample.
Since:
  • 4.0.0
Source:
Returns:
Returns the random elements.
Type
Array
Example
_.sampleSize([1, 2, 3], 2);
// => [3, 1]

_.sampleSize([1, 2, 3], 4);
// => [2, 3, 1]

(static) sampleSize(collection, nopt) → {Array}

Gets `n` random elements at unique keys from `collection` up to the size of `collection`.
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to sample.
n number <optional>
1 The number of elements to sample.
Since:
  • 4.0.0
Source:
Returns:
Returns the random elements.
Type
Array
Example
_.sampleSize([1, 2, 3], 2);
// => [3, 1]

_.sampleSize([1, 2, 3], 4);
// => [2, 3, 1]

(static) set(object, path, value) → {Object}

Sets the value at `path` of `object`. If a portion of `path` doesn't exist, it's created. Arrays are created for missing index properties while objects are created for all other missing properties. Use `_.setWith` to customize `path` creation. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
Since:
  • 3.7.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// => 4

_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// => 5

(static) set(object, path, value) → {Object}

Sets the value at `path` of `object`. If a portion of `path` doesn't exist, it's created. Arrays are created for missing index properties while objects are created for all other missing properties. Use `_.setWith` to customize `path` creation. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
Since:
  • 3.7.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// => 4

_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// => 5

(static) setWith(object, path, value, customizeropt) → {Object}

This method is like `_.set` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.0.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.setWith(object, '[0][1]', 'a', Object);
// => { '0': { '1': 'a' } }

(static) setWith(object, path, value, customizeropt) → {Object}

This method is like `_.set` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
value * The value to set.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.0.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.setWith(object, '[0][1]', 'a', Object);
// => { '0': { '1': 'a' } }

(static) shuffle(collection) → {Array}

Creates an array of shuffled values, using a version of the [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
Parameters:
Name Type Description
collection Array | Object The collection to shuffle.
Since:
  • 0.1.0
Source:
Returns:
Returns the new shuffled array.
Type
Array
Example
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]

(static) shuffle(collection) → {Array}

Creates an array of shuffled values, using a version of the [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
Parameters:
Name Type Description
collection Array | Object The collection to shuffle.
Since:
  • 0.1.0
Source:
Returns:
Returns the new shuffled array.
Type
Array
Example
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) size(collection) → {number}

Gets the size of `collection` by returning its length for array-like values or the number of own enumerable string keyed properties for objects.
Parameters:
Name Type Description
collection Array | Object | string The collection to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the collection size.
Type
number
Example
_.size([1, 2, 3]);
// => 3

_.size({ 'a': 1, 'b': 2 });
// => 2

_.size('pebbles');
// => 7

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) slice(array, startopt, endopt) → {Array}

Creates a slice of `array` from `start` up to, but not including, `end`. **Note:** This method is used instead of [`Array#slice`](https://mdn.io/Array/slice) to ensure dense arrays are returned.
Parameters:
Name Type Attributes Default Description
array Array The array to slice.
start number <optional>
0 The start position.
end number <optional>
array.length The end position.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) some(collection, predicateopt) → {boolean}

Checks if `predicate` returns truthy for **any** element of `collection`. Iteration is stopped once `predicate` returns truthy. The predicate is invoked with three arguments: (value, index|key, collection).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns `true` if any element passes the predicate check, else `false`.
Type
boolean
Example
_.some([null, 0, 'yes', false], Boolean);
// => true

var users = [
  { 'user': 'barney', 'active': true },
  { 'user': 'fred',   'active': false }
];

// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// => false

// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// => true

// The `_.property` iteratee shorthand.
_.some(users, 'active');
// => true

(static) sortBy(collection, …iterateesopt) → {Array}

Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
collection Array | Object The collection to iterate over.
iteratees function | Array:.<function()> <optional>
<repeatable>
[_.identity] The iteratees to sort by.
Since:
  • 0.1.0
Source:
Returns:
Returns the new sorted array.
Type
Array
Example
var users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 30 },
  { 'user': 'barney', 'age': 34 }
];

_.sortBy(users, [function(o) { return o.user; }]);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 30]]

_.sortBy(users, ['user', 'age']);
// => objects for [['barney', 34], ['barney', 36], ['fred', 30], ['fred', 48]]

(static) sortedIndex(array, value) → {number}

Uses a binary search to determine the lowest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 0.1.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedIndex([30, 50], 40);
// => 1

(static) sortedIndex(array, value) → {number}

Uses a binary search to determine the lowest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 0.1.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedIndex([30, 50], 40);
// => 1

(static) sortedIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 0

// The `_.property` iteratee shorthand.
_.sortedIndexBy(objects, { 'x': 4 }, 'x');
// => 0

(static) sortedIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 0

// The `_.property` iteratee shorthand.
_.sortedIndexBy(objects, { 'x': 4 }, 'x');
// => 0

(static) sortedIndexOf(array, value) → {number}

This method is like `_.indexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5);
// => 1

(static) sortedIndexOf(array, value) → {number}

This method is like `_.indexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedIndexOf([4, 5, 5, 5, 6], 5);
// => 1

(static) sortedLastIndex(array, value) → {number}

This method is like `_.sortedIndex` except that it returns the highest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 3.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5);
// => 4

(static) sortedLastIndex(array, value) → {number}

This method is like `_.sortedIndex` except that it returns the highest index at which `value` should be inserted into `array` in order to maintain its sort order.
Parameters:
Name Type Description
array Array The sorted array to inspect.
value * The value to evaluate.
Since:
  • 3.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
_.sortedLastIndex([4, 5, 5, 5, 6], 5);
// => 4

(static) sortedLastIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedLastIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 1

// The `_.property` iteratee shorthand.
_.sortedLastIndexBy(objects, { 'x': 4 }, 'x');
// => 1

(static) sortedLastIndexBy(array, value, iterateeopt) → {number}

This method is like `_.sortedLastIndex` except that it accepts `iteratee` which is invoked for `value` and each element of `array` to compute their sort ranking. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The sorted array to inspect.
value * The value to evaluate.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the index at which `value` should be inserted into `array`.
Type
number
Example
var objects = [{ 'x': 4 }, { 'x': 5 }];

_.sortedLastIndexBy(objects, { 'x': 4 }, function(o) { return o.x; });
// => 1

// The `_.property` iteratee shorthand.
_.sortedLastIndexBy(objects, { 'x': 4 }, 'x');
// => 1

(static) sortedLastIndexOf(array, value) → {number}

This method is like `_.lastIndexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5);
// => 3

(static) sortedLastIndexOf(array, value) → {number}

This method is like `_.lastIndexOf` except that it performs a binary search on a sorted `array`.
Parameters:
Name Type Description
array Array The array to inspect.
value * The value to search for.
Since:
  • 4.0.0
Source:
Returns:
Returns the index of the matched value, else `-1`.
Type
number
Example
_.sortedLastIndexOf([4, 5, 5, 5, 6], 5);
// => 3

(static) sortedUniq(array) → {Array}

This method is like `_.uniq` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniq([1, 1, 2]);
// => [1, 2]

(static) sortedUniq(array) → {Array}

This method is like `_.uniq` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniq([1, 1, 2]);
// => [1, 2]

(static) sortedUniqBy(array, iterateeopt) → {Array}

This method is like `_.uniqBy` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Attributes Description
array Array The array to inspect.
iteratee function <optional>
The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// => [1.1, 2.3]

(static) sortedUniqBy(array, iterateeopt) → {Array}

This method is like `_.uniqBy` except that it's designed and optimized for sorted arrays.
Parameters:
Name Type Attributes Description
array Array The array to inspect.
iteratee function <optional>
The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// => [1.1, 2.3]

(static) split(stringopt, separator, limitopt) → {Array}

Splits `string` by `separator`. **Note:** This method is based on [`String#split`](https://mdn.io/String/split).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to split.
separator RegExp | string The separator pattern to split by.
limit number <optional>
The length to truncate results to.
Since:
  • 4.0.0
Source:
Returns:
Returns the string segments.
Type
Array
Example
_.split('a-b-c', '-', 2);
// => ['a', 'b']

(static) split(stringopt, separator, limitopt) → {Array}

Splits `string` by `separator`. **Note:** This method is based on [`String#split`](https://mdn.io/String/split).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to split.
separator RegExp | string The separator pattern to split by.
limit number <optional>
The length to truncate results to.
Since:
  • 4.0.0
Source:
Returns:
Returns the string segments.
Type
Array
Example
_.split('a-b-c', '-', 2);
// => ['a', 'b']

(static) spread(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the create function and an array of arguments much like [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply). **Note:** This method is based on the [spread operator](https://mdn.io/spread_operator).
Parameters:
Name Type Attributes Default Description
func function The function to spread arguments over.
start number <optional>
0 The start position of the spread.
Since:
  • 3.2.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.spread(function(who, what) {
  return who + ' says ' + what;
});

say(['fred', 'hello']);
// => 'fred says hello'

var numbers = Promise.all([
  Promise.resolve(40),
  Promise.resolve(36)
]);

numbers.then(_.spread(function(x, y) {
  return x + y;
}));
// => a Promise of 76

(static) spread(func, startopt) → {function}

Creates a function that invokes `func` with the `this` binding of the create function and an array of arguments much like [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply). **Note:** This method is based on the [spread operator](https://mdn.io/spread_operator).
Parameters:
Name Type Attributes Default Description
func function The function to spread arguments over.
start number <optional>
0 The start position of the spread.
Since:
  • 3.2.0
Source:
Returns:
Returns the new function.
Type
function
Example
var say = _.spread(function(who, what) {
  return who + ' says ' + what;
});

say(['fred', 'hello']);
// => 'fred says hello'

var numbers = Promise.all([
  Promise.resolve(40),
  Promise.resolve(36)
]);

numbers.then(_.spread(function(x, y) {
  return x + y;
}));
// => a Promise of 76

(static) startsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` starts with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
0 The position to search from.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` starts with `target`, else `false`.
Type
boolean
Example
_.startsWith('abc', 'a');
// => true

_.startsWith('abc', 'b');
// => false

_.startsWith('abc', 'b', 1);
// => true

(static) startsWith(stringopt, targetopt, positionopt) → {boolean}

Checks if `string` starts with the given target string.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
target string <optional>
The string to search for.
position number <optional>
0 The position to search from.
Since:
  • 3.0.0
Source:
Returns:
Returns `true` if `string` starts with `target`, else `false`.
Type
boolean
Example
_.startsWith('abc', 'a');
// => true

_.startsWith('abc', 'b');
// => false

_.startsWith('abc', 'b', 1);
// => true

(static) stubArray() → {Array}

This method returns a new empty array.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty array.
Type
Array
Example
var arrays = _.times(2, _.stubArray);

console.log(arrays);
// => [[], []]

console.log(arrays[0] === arrays[1]);
// => false

(static) stubArray() → {Array}

This method returns a new empty array.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty array.
Type
Array
Example
var arrays = _.times(2, _.stubArray);

console.log(arrays);
// => [[], []]

console.log(arrays[0] === arrays[1]);
// => false

(static) stubFalse() → {boolean}

This method returns `false`.
Since:
  • 4.13.0
Source:
Returns:
Returns `false`.
Type
boolean
Example
_.times(2, _.stubFalse);
// => [false, false]

(static) stubFalse() → {boolean}

This method returns `false`.
Since:
  • 4.13.0
Source:
Returns:
Returns `false`.
Type
boolean
Example
_.times(2, _.stubFalse);
// => [false, false]

(static) stubObject() → {Object}

This method returns a new empty object.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty object.
Type
Object
Example
var objects = _.times(2, _.stubObject);

console.log(objects);
// => [{}, {}]

console.log(objects[0] === objects[1]);
// => false

(static) stubObject() → {Object}

This method returns a new empty object.
Since:
  • 4.13.0
Source:
Returns:
Returns the new empty object.
Type
Object
Example
var objects = _.times(2, _.stubObject);

console.log(objects);
// => [{}, {}]

console.log(objects[0] === objects[1]);
// => false

(static) stubString() → {string}

This method returns an empty string.
Since:
  • 4.13.0
Source:
Returns:
Returns the empty string.
Type
string
Example
_.times(2, _.stubString);
// => ['', '']

(static) stubString() → {string}

This method returns an empty string.
Since:
  • 4.13.0
Source:
Returns:
Returns the empty string.
Type
string
Example
_.times(2, _.stubString);
// => ['', '']

(static) stubTrue() → {boolean}

This method returns `true`.
Since:
  • 4.13.0
Source:
Returns:
Returns `true`.
Type
boolean
Example
_.times(2, _.stubTrue);
// => [true, true]

(static) stubTrue() → {boolean}

This method returns `true`.
Since:
  • 4.13.0
Source:
Returns:
Returns `true`.
Type
boolean
Example
_.times(2, _.stubTrue);
// => [true, true]

(static) sum(array) → {number}

Computes the sum of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 3.4.0
Source:
Returns:
Returns the sum.
Type
number
Example
_.sum([4, 2, 8, 6]);
// => 20

(static) sum(array) → {number}

Computes the sum of the values in `array`.
Parameters:
Name Type Description
array Array The array to iterate over.
Since:
  • 3.4.0
Source:
Returns:
Returns the sum.
Type
number
Example
_.sum([4, 2, 8, 6]);
// => 20

(static) sumBy(array, iterateeopt) → {number}

This method is like `_.sum` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be summed. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the sum.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.sumBy(objects, function(o) { return o.n; });
// => 20

// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20

(static) sumBy(array, iterateeopt) → {number}

This method is like `_.sum` except that it accepts `iteratee` which is invoked for each element in `array` to generate the value to be summed. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to iterate over.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the sum.
Type
number
Example
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];

_.sumBy(objects, function(o) { return o.n; });
// => 20

// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// => 20

(static) tail(array) → {Array}

Gets all but the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 4.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.tail([1, 2, 3]);
// => [2, 3]

(static) tail(array) → {Array}

Gets all but the first element of `array`.
Parameters:
Name Type Description
array Array The array to query.
Since:
  • 4.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.tail([1, 2, 3]);
// => [2, 3]

(static) take(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.take([1, 2, 3]);
// => [1]

_.take([1, 2, 3], 2);
// => [1, 2]

_.take([1, 2, 3], 5);
// => [1, 2, 3]

_.take([1, 2, 3], 0);
// => []

(static) take(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the beginning.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 0.1.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.take([1, 2, 3]);
// => [1]

_.take([1, 2, 3], 2);
// => [1, 2]

_.take([1, 2, 3], 5);
// => [1, 2, 3]

_.take([1, 2, 3], 0);
// => []

(static) takeRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

_.takeRight([1, 2, 3], 0);
// => []

(static) takeRight(array, nopt) → {Array}

Creates a slice of `array` with `n` elements taken from the end.
Parameters:
Name Type Attributes Default Description
array Array The array to query.
n number <optional>
1 The number of elements to take.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

_.takeRight([1, 2, 3], 0);
// => []

(static) takeRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the end. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.takeRightWhile(users, function(o) { return !o.active; });
// => objects for ['fred', 'pebbles']

// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// => objects for ['fred', 'pebbles']

// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// => []

(static) takeRightWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the end. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': true },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': false }
];

_.takeRightWhile(users, function(o) { return !o.active; });
// => objects for ['fred', 'pebbles']

// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// => objects for ['pebbles']

// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// => objects for ['fred', 'pebbles']

// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// => []

(static) takeWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the beginning. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.takeWhile(users, function(o) { return !o.active; });
// => objects for ['barney', 'fred']

// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// => objects for ['barney', 'fred']

// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// => []

(static) takeWhile(array, predicateopt) → {Array}

Creates a slice of `array` with elements taken from the beginning. Elements are taken until `predicate` returns falsey. The predicate is invoked with three arguments: (value, index, array).
Parameters:
Name Type Attributes Default Description
array Array The array to query.
predicate function <optional>
_.identity The function invoked per iteration.
Since:
  • 3.0.0
Source:
Returns:
Returns the slice of `array`.
Type
Array
Example
var users = [
  { 'user': 'barney',  'active': false },
  { 'user': 'fred',    'active': false },
  { 'user': 'pebbles', 'active': true }
];

_.takeWhile(users, function(o) { return !o.active; });
// => objects for ['barney', 'fred']

// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// => objects for ['barney']

// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// => objects for ['barney', 'fred']

// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// => []

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) tap(value, interceptor) → {*}

This method invokes `interceptor` and returns `value`. The interceptor is invoked with one argument; (value). The purpose of this method is to "tap into" a method chain sequence in order to modify intermediate results.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 0.1.0
Source:
Returns:
Returns `value`.
Type
*
Example
_([1, 2, 3])
 .tap(function(array) {
   // Mutate input array.
   array.pop();
 })
 .reverse()
 .value();
// => [2, 1]

(static) template(stringopt, optionsopt) → {function}

Creates a compiled template function that can interpolate data properties in "interpolate" delimiters, HTML-escape interpolated data properties in "escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data properties may be accessed as free variables in the template. If a setting object is given, it takes precedence over `_.templateSettings` values. **Note:** In the development build `_.template` utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging. For more information on precompiling templates see [lodash's custom builds documentation](https://lodash.com/custom-builds). For more information on Chrome extension sandboxes see [Chrome's extensions documentation](https://developer.chrome.com/extensions/sandboxingEval).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The template string.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
escape RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL string <optional>
'lodash.templateSources[n]' The sourceURL of the compiled template.
variable string <optional>
'obj' The data object variable name.
Since:
  • 0.1.0
Source:
Returns:
Returns the compiled template function.
Type
function
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'

// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b>&lt;script&gt;</b>'

// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'

// Use the ES template literal delimiter as an "interpolate" delimiter.
// Disable support by replacing the "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'

// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'

// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.

// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// => function(data) {
//   var __t, __p = '';
//   __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
//   return __p;
// }

// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'

// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\
  var JST = {\
    "main": ' + _.template(mainText).source + '\
  };\
');

(static) template(stringopt, optionsopt) → {function}

Creates a compiled template function that can interpolate data properties in "interpolate" delimiters, HTML-escape interpolated data properties in "escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data properties may be accessed as free variables in the template. If a setting object is given, it takes precedence over `_.templateSettings` values. **Note:** In the development build `_.template` utilizes [sourceURLs](http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl) for easier debugging. For more information on precompiling templates see [lodash's custom builds documentation](https://lodash.com/custom-builds). For more information on Chrome extension sandboxes see [Chrome's extensions documentation](https://developer.chrome.com/extensions/sandboxingEval).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The template string.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
escape RegExp <optional>
_.templateSettings.escape The HTML "escape" delimiter.
evaluate RegExp <optional>
_.templateSettings.evaluate The "evaluate" delimiter.
imports Object <optional>
_.templateSettings.imports An object to import into the template as free variables.
interpolate RegExp <optional>
_.templateSettings.interpolate The "interpolate" delimiter.
sourceURL string <optional>
'templateSources[n]' The sourceURL of the compiled template.
variable string <optional>
'obj' The data object variable name.
Since:
  • 0.1.0
Source:
Returns:
Returns the compiled template function.
Type
function
Example
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'

// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b>&lt;script&gt;</b>'

// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'

// Use the ES template literal delimiter as an "interpolate" delimiter.
// Disable support by replacing the "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'

// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'

// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'

// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// => Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.

// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// => function(data) {
//   var __t, __p = '';
//   __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
//   return __p;
// }

// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'

// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(process.cwd(), 'jst.js'), '\
  var JST = {\
    "main": ' + _.template(mainText).source + '\
  };\
');

(static) throttle(func, waitopt, optionsopt) → {function}

Creates a throttled function that only invokes `func` at most once per every `wait` milliseconds. The throttled function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the throttled function. Subsequent calls to the throttled function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the throttled function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.throttle` and `_.debounce`.
Parameters:
Name Type Attributes Default Description
func function The function to throttle.
wait number <optional>
0 The number of milliseconds to throttle invocations to.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new throttled function.
Type
function
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));

// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);

// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);

(static) throttle(func, waitopt, optionsopt) → {function}

Creates a throttled function that only invokes `func` at most once per every `wait` milliseconds. The throttled function comes with a `cancel` method to cancel delayed `func` invocations and a `flush` method to immediately invoke them. Provide `options` to indicate whether `func` should be invoked on the leading and/or trailing edge of the `wait` timeout. The `func` is invoked with the last arguments provided to the throttled function. Subsequent calls to the throttled function return the result of the last `func` invocation. **Note:** If `leading` and `trailing` options are `true`, `func` is invoked on the trailing edge of the timeout only if the throttled function is invoked more than once during the `wait` timeout. If `wait` is `0` and `leading` is `false`, `func` invocation is deferred until to the next tick, similar to `setTimeout` with a timeout of `0`. See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/) for details over the differences between `_.throttle` and `_.debounce`.
Parameters:
Name Type Attributes Default Description
func function The function to throttle.
wait number <optional>
0 The number of milliseconds to throttle invocations to.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
leading boolean <optional>
true Specify invoking on the leading edge of the timeout.
trailing boolean <optional>
true Specify invoking on the trailing edge of the timeout.
Since:
  • 0.1.0
Source:
Returns:
Returns the new throttled function.
Type
function
Example
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));

// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);

// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) thru(value, interceptor) → {*}

This method is like `_.tap` except that it returns the result of `interceptor`. The purpose of this method is to "pass thru" values replacing intermediate results in a method chain sequence.
Parameters:
Name Type Description
value * The value to provide to `interceptor`.
interceptor function The function to invoke.
Since:
  • 3.0.0
Source:
Returns:
Returns the result of `interceptor`.
Type
*
Example
_('  abc  ')
 .chain()
 .trim()
 .thru(function(value) {
   return [value];
 })
 .value();
// => ['abc']

(static) times(n, iterateeopt) → {Array}

Invokes the iteratee `n` times, returning an array of the results of each invocation. The iteratee is invoked with one argument; (index).
Parameters:
Name Type Attributes Default Description
n number The number of times to invoke `iteratee`.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of results.
Type
Array
Example
_.times(3, String);
// => ['0', '1', '2']

 _.times(4, _.constant(0));
// => [0, 0, 0, 0]

(static) times(n, iterateeopt) → {Array}

Invokes the iteratee `n` times, returning an array of the results of each invocation. The iteratee is invoked with one argument; (index).
Parameters:
Name Type Attributes Default Description
n number The number of times to invoke `iteratee`.
iteratee function <optional>
_.identity The function invoked per iteration.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of results.
Type
Array
Example
_.times(3, String);
// => ['0', '1', '2']

 _.times(4, _.constant(0));
// => [0, 0, 0, 0]

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toArray(value) → {Array}

Converts `value` to an array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 0.1.0
Source:
Returns:
Returns the converted array.
Type
Array
Example
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]

_.toArray('abc');
// => ['a', 'b', 'c']

_.toArray(1);
// => []

_.toArray(null);
// => []

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toFinite(value) → {number}

Converts `value` to a finite number.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.12.0
Source:
Returns:
Returns the converted number.
Type
number
Example
_.toFinite(3.2);
// => 3.2

_.toFinite(Number.MIN_VALUE);
// => 5e-324

_.toFinite(Infinity);
// => 1.7976931348623157e+308

_.toFinite('3.2');
// => 3.2

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toInteger(value) → {number}

Converts `value` to an integer. **Note:** This method is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/7.0/#sec-tointeger).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toInteger(3.2);
// => 3

_.toInteger(Number.MIN_VALUE);
// => 0

_.toInteger(Infinity);
// => 1.7976931348623157e+308

_.toInteger('3.2');
// => 3

(static) toLength(value) → {number}

Converts `value` to an integer suitable for use as the length of an array-like object. **Note:** This method is based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toLength(3.2);
// => 3

_.toLength(Number.MIN_VALUE);
// => 0

_.toLength(Infinity);
// => 4294967295

_.toLength('3.2');
// => 3

(static) toLength(value) → {number}

Converts `value` to an integer suitable for use as the length of an array-like object. **Note:** This method is based on [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toLength(3.2);
// => 3

_.toLength(Number.MIN_VALUE);
// => 0

_.toLength(Infinity);
// => 4294967295

_.toLength('3.2');
// => 3

(static) toLower(stringopt) → {string}

Converts `string`, as a whole, to lower case just like [String#toLowerCase](https://mdn.io/toLowerCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the lower cased string.
Type
string
Example
_.toLower('--Foo-Bar--');
// => '--foo-bar--'

_.toLower('fooBar');
// => 'foobar'

_.toLower('__FOO_BAR__');
// => '__foo_bar__'

(static) toLower(stringopt) → {string}

Converts `string`, as a whole, to lower case just like [String#toLowerCase](https://mdn.io/toLowerCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the lower cased string.
Type
string
Example
_.toLower('--Foo-Bar--');
// => '--foo-bar--'

_.toLower('fooBar');
// => 'foobar'

_.toLower('__FOO_BAR__');
// => '__foo_bar__'

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toNumber(value) → {number}

Converts `value` to a number.
Parameters:
Name Type Description
value * The value to process.
Since:
  • 4.0.0
Source:
Returns:
Returns the number.
Type
number
Example
_.toNumber(3.2);
// => 3.2

_.toNumber(Number.MIN_VALUE);
// => 5e-324

_.toNumber(Infinity);
// => Infinity

_.toNumber('3.2');
// => 3.2

(static) toPath(value) → {Array}

Converts `value` to a property path array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the new property path array.
Type
Array
Example
_.toPath('a.b.c');
// => ['a', 'b', 'c']

_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']

(static) toPath(value) → {Array}

Converts `value` to a property path array.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the new property path array.
Type
Array
Example
_.toPath('a.b.c');
// => ['a', 'b', 'c']

_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']

(static) toPlainObject(value) → {Object}

Converts `value` to a plain object flattening inherited enumerable string keyed properties of `value` to own properties of the plain object.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 3.0.0
Source:
Returns:
Returns the converted plain object.
Type
Object
Example
function Foo() {
  this.b = 2;
}

Foo.prototype.c = 3;

_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }

_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }

(static) toPlainObject(value) → {Object}

Converts `value` to a plain object flattening inherited enumerable string keyed properties of `value` to own properties of the plain object.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 3.0.0
Source:
Returns:
Returns the converted plain object.
Type
Object
Example
function Foo() {
  this.b = 2;
}

Foo.prototype.c = 3;

_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }

_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }

(static) toSafeInteger(value) → {number}

Converts `value` to a safe integer. A safe integer can be compared and represented correctly.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toSafeInteger(3.2);
// => 3

_.toSafeInteger(Number.MIN_VALUE);
// => 0

_.toSafeInteger(Infinity);
// => 9007199254740991

_.toSafeInteger('3.2');
// => 3

(static) toSafeInteger(value) → {number}

Converts `value` to a safe integer. A safe integer can be compared and represented correctly.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted integer.
Type
number
Example
_.toSafeInteger(3.2);
// => 3

_.toSafeInteger(Number.MIN_VALUE);
// => 0

_.toSafeInteger(Infinity);
// => 9007199254740991

_.toSafeInteger('3.2');
// => 3

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toString(value) → {string}

Converts `value` to a string. An empty string is returned for `null` and `undefined` values. The sign of `-0` is preserved.
Parameters:
Name Type Description
value * The value to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the converted string.
Type
string
Example
_.toString(null);
// => ''

_.toString(-0);
// => '-0'

_.toString([1, 2, 3]);
// => '1,2,3'

(static) toUpper(stringopt) → {string}

Converts `string`, as a whole, to upper case just like [String#toUpperCase](https://mdn.io/toUpperCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the upper cased string.
Type
string
Example
_.toUpper('--foo-bar--');
// => '--FOO-BAR--'

_.toUpper('fooBar');
// => 'FOOBAR'

_.toUpper('__foo_bar__');
// => '__FOO_BAR__'

(static) toUpper(stringopt) → {string}

Converts `string`, as a whole, to upper case just like [String#toUpperCase](https://mdn.io/toUpperCase).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to convert.
Since:
  • 4.0.0
Source:
Returns:
Returns the upper cased string.
Type
string
Example
_.toUpper('--foo-bar--');
// => '--FOO-BAR--'

_.toUpper('fooBar');
// => 'FOOBAR'

_.toUpper('__foo_bar__');
// => '__FOO_BAR__'

(static) transform(object, iterateeopt, accumulatoropt) → {*}

An alternative to `_.reduce`; this method transforms `object` to a new `accumulator` object which is the result of running each of its own enumerable string keyed properties thru `iteratee`, with each invocation potentially mutating the `accumulator` object. If `accumulator` is not provided, a new object with the same `[[Prototype]]` will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The custom accumulator value.
Since:
  • 1.3.0
Source:
Returns:
Returns the accumulated value.
Type
*
Example
_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
}, []);
// => [4, 9]

_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
}, {});
// => { '1': ['a', 'c'], '2': ['b'] }

(static) transform(object, iterateeopt, accumulatoropt) → {*}

An alternative to `_.reduce`; this method transforms `object` to a new `accumulator` object which is the result of running each of its own enumerable string keyed properties thru `iteratee`, with each invocation potentially mutating the `accumulator` object. If `accumulator` is not provided, a new object with the same `[[Prototype]]` will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning `false`.
Parameters:
Name Type Attributes Default Description
object Object The object to iterate over.
iteratee function <optional>
_.identity The function invoked per iteration.
accumulator * <optional>
The custom accumulator value.
Since:
  • 1.3.0
Source:
Returns:
Returns the accumulated value.
Type
*
Example
_.transform([2, 3, 4], function(result, n) {
  result.push(n *= n);
  return n % 2 == 0;
}, []);
// => [4, 9]

_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
  (result[value] || (result[value] = [])).push(key);
}, {});
// => { '1': ['a', 'c'], '2': ['b'] }

(static) trim(stringopt, charsopt) → {string}

Removes leading and trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 3.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trim('  abc  ');
// => 'abc'

_.trim('-_-abc-_-', '_-');
// => 'abc'

_.map(['  foo  ', '  bar  '], _.trim);
// => ['foo', 'bar']

(static) trim(stringopt, charsopt) → {string}

Removes leading and trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 3.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trim('  abc  ');
// => 'abc'

_.trim('-_-abc-_-', '_-');
// => 'abc'

_.map(['  foo  ', '  bar  '], _.trim);
// => ['foo', 'bar']

(static) trimEnd(stringopt, charsopt) → {string}

Removes trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimEnd('  abc  ');
// => '  abc'

_.trimEnd('-_-abc-_-', '_-');
// => '-_-abc'

(static) trimEnd(stringopt, charsopt) → {string}

Removes trailing whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimEnd('  abc  ');
// => '  abc'

_.trimEnd('-_-abc-_-', '_-');
// => '-_-abc'

(static) trimStart(stringopt, charsopt) → {string}

Removes leading whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimStart('  abc  ');
// => 'abc  '

_.trimStart('-_-abc-_-', '_-');
// => 'abc-_-'

(static) trimStart(stringopt, charsopt) → {string}

Removes leading whitespace or specified characters from `string`.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to trim.
chars string <optional>
whitespace The characters to trim.
Since:
  • 4.0.0
Source:
Returns:
Returns the trimmed string.
Type
string
Example
_.trimStart('  abc  ');
// => 'abc  '

_.trimStart('-_-abc-_-', '_-');
// => 'abc-_-'

(static) truncate(stringopt, optionsopt) → {string}

Truncates `string` if it's longer than the given maximum string length. The last characters of the truncated string are replaced with the omission string which defaults to "...".
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to truncate.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
length number <optional>
30 The maximum string length.
omission string <optional>
'...' The string to indicate text is omitted.
separator RegExp | string <optional>
The separator pattern to truncate to.
Since:
  • 4.0.0
Source:
Returns:
Returns the truncated string.
Type
string
Example
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': ' '
});
// => 'hi-diddly-ho there,...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': /,? +/
});
// => 'hi-diddly-ho there...'

_.truncate('hi-diddly-ho there, neighborino', {
  'omission': ' [...]'
});
// => 'hi-diddly-ho there, neig [...]'

(static) truncate(stringopt, optionsopt) → {string}

Truncates `string` if it's longer than the given maximum string length. The last characters of the truncated string are replaced with the omission string which defaults to "...".
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to truncate.
options Object <optional>
{} The options object.
Properties
Name Type Attributes Default Description
length number <optional>
30 The maximum string length.
omission string <optional>
'...' The string to indicate text is omitted.
separator RegExp | string <optional>
The separator pattern to truncate to.
Since:
  • 4.0.0
Source:
Returns:
Returns the truncated string.
Type
string
Example
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': ' '
});
// => 'hi-diddly-ho there,...'

_.truncate('hi-diddly-ho there, neighborino', {
  'length': 24,
  'separator': /,? +/
});
// => 'hi-diddly-ho there...'

_.truncate('hi-diddly-ho there, neighborino', {
  'omission': ' [...]'
});
// => 'hi-diddly-ho there, neig [...]'

(static) unary(func) → {function}

Creates a function that accepts up to one argument, ignoring any additional arguments.
Parameters:
Name Type Description
func function The function to cap arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// => [6, 8, 10]

(static) unary(func) → {function}

Creates a function that accepts up to one argument, ignoring any additional arguments.
Parameters:
Name Type Description
func function The function to cap arguments for.
Since:
  • 4.0.0
Source:
Returns:
Returns the new capped function.
Type
function
Example
_.map(['6', '8', '10'], _.unary(parseInt));
// => [6, 8, 10]

(static) unescape(stringopt) → {string}

The inverse of `_.escape`; this method converts the HTML entities `&`, `<`, `>`, `"`, and `'` in `string` to their corresponding characters. **Note:** No other HTML entities are unescaped. To unescape additional HTML entities use a third-party library like [_he_](https://mths.be/he).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to unescape.
Since:
  • 0.6.0
Source:
Returns:
Returns the unescaped string.
Type
string
Example
_.unescape('fred, barney, &amp; pebbles');
// => 'fred, barney, & pebbles'

(static) unescape(stringopt) → {string}

The inverse of `_.escape`; this method converts the HTML entities `&`, `<`, `>`, `"`, and `'` in `string` to their corresponding characters. **Note:** No other HTML entities are unescaped. To unescape additional HTML entities use a third-party library like [_he_](https://mths.be/he).
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to unescape.
Since:
  • 0.6.0
Source:
Returns:
Returns the unescaped string.
Type
string
Example
_.unescape('fred, barney, &amp; pebbles');
// => 'fred, barney, & pebbles'

(static) uniq(array) → {Array}

Creates a duplicate-free version of an array, using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniq([2, 1, 2]);
// => [2, 1]

(static) uniq(array) → {Array}

Creates a duplicate-free version of an array, using [`SameValueZero`](http://ecma-international.org/ecma-262/7.0/#sec-samevaluezero) for equality comparisons, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
Parameters:
Name Type Description
array Array The array to inspect.
Since:
  • 0.1.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniq([2, 1, 2]);
// => [2, 1]

(static) uniqBy(array, iterateeopt) → {Array}

This method is like `_.uniq` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which uniqueness is computed. The order of result values is determined by the order they occur in the array. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) uniqBy(array, iterateeopt) → {Array}

This method is like `_.uniq` except that it accepts `iteratee` which is invoked for each element in `array` to generate the criterion by which uniqueness is computed. The order of result values is determined by the order they occur in the array. The iteratee is invoked with one argument: (value).
Parameters:
Name Type Attributes Default Description
array Array The array to inspect.
iteratee function <optional>
_.identity The iteratee invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

(static) uniqWith(array, comparatoropt) → {Array}

This method is like `_.uniq` except that it accepts `comparator` which is invoked to compare elements of `array`. The order of result values is determined by the order they occur in the array.The comparator is invoked with two arguments: (arrVal, othVal).
Parameters:
Name Type Attributes Description
array Array The array to inspect.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

(static) uniqWith(array, comparatoropt) → {Array}

This method is like `_.uniq` except that it accepts `comparator` which is invoked to compare elements of `array`. The order of result values is determined by the order they occur in the array.The comparator is invoked with two arguments: (arrVal, othVal).
Parameters:
Name Type Attributes Description
array Array The array to inspect.
comparator function <optional>
The comparator invoked per element.
Since:
  • 4.0.0
Source:
Returns:
Returns the new duplicate free array.
Type
Array
Example
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) uniqueId(prefixopt) → {string}

Generates a unique ID. If `prefix` is given, the ID is appended to it.
Parameters:
Name Type Attributes Default Description
prefix string <optional>
'' The value to prefix the ID with.
Since:
  • 0.1.0
Source:
Returns:
Returns the unique ID.
Type
string
Example
_.uniqueId('contact_');
// => 'contact_104'

_.uniqueId();
// => '105'

(static) unset(object, path) → {boolean}

Removes the property at `path` of `object`. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to unset.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the property is deleted, else `false`.
Type
boolean
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

_.unset(object, ['a', '0', 'b', 'c']);
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

(static) unset(object, path) → {boolean}

Removes the property at `path` of `object`. **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to unset.
Since:
  • 4.0.0
Source:
Returns:
Returns `true` if the property is deleted, else `false`.
Type
boolean
Example
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

_.unset(object, ['a', '0', 'b', 'c']);
// => true

console.log(object);
// => { 'a': [{ 'b': {} }] };

(static) unzip(array) → {Array}

This method is like `_.zip` except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.
Parameters:
Name Type Description
array Array The array of grouped elements to process.
Since:
  • 1.2.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

_.unzip(zipped);
// => [['a', 'b'], [1, 2], [true, false]]

(static) unzip(array) → {Array}

This method is like `_.zip` except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.
Parameters:
Name Type Description
array Array The array of grouped elements to process.
Since:
  • 1.2.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip(['a', 'b'], [1, 2], [true, false]);
// => [['a', 1, true], ['b', 2, false]]

_.unzip(zipped);
// => [['a', 'b'], [1, 2], [true, false]]

(static) unzipWith(array, iterateeopt) → {Array}

This method is like `_.unzip` except that it accepts `iteratee` to specify how regrouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Parameters:
Name Type Attributes Default Description
array Array The array of grouped elements to process.
iteratee function <optional>
_.identity The function to combine regrouped values.
Since:
  • 3.8.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]

_.unzipWith(zipped, _.add);
// => [3, 30, 300]

(static) unzipWith(array, iterateeopt) → {Array}

This method is like `_.unzip` except that it accepts `iteratee` to specify how regrouped values should be combined. The iteratee is invoked with the elements of each group: (...group).
Parameters:
Name Type Attributes Default Description
array Array The array of grouped elements to process.
iteratee function <optional>
_.identity The function to combine regrouped values.
Since:
  • 3.8.0
Source:
Returns:
Returns the new array of regrouped elements.
Type
Array
Example
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]

_.unzipWith(zipped, _.add);
// => [3, 30, 300]

(static) update(object, path, updater) → {Object}

This method is like `_.set` except that accepts `updater` to produce the value to set. Use `_.updateWith` to customize `path` creation. The `updater` is invoked with one argument: (value). **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// => 9

_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// => 0

(static) update(object, path, updater) → {Object}

This method is like `_.set` except that accepts `updater` to produce the value to set. Use `_.updateWith` to customize `path` creation. The `updater` is invoked with one argument: (value). **Note:** This method mutates `object`.
Parameters:
Name Type Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = { 'a': [{ 'b': { 'c': 3 } }] };

_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// => 9

_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// => 0

(static) updateWith(object, path, updater, customizeropt) → {Object}

This method is like `_.update` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.updateWith(object, '[0][1]', _.constant('a'), Object);
// => { '0': { '1': 'a' } }

(static) updateWith(object, path, updater, customizeropt) → {Object}

This method is like `_.update` except that it accepts `customizer` which is invoked to produce the objects of `path`. If `customizer` returns `undefined` path creation is handled by the method instead. The `customizer` is invoked with three arguments: (nsValue, key, nsObject). **Note:** This method mutates `object`.
Parameters:
Name Type Attributes Description
object Object The object to modify.
path Array | string The path of the property to set.
updater function The function to produce the updated value.
customizer function <optional>
The function to customize assigned values.
Since:
  • 4.6.0
Source:
Returns:
Returns `object`.
Type
Object
Example
var object = {};

_.updateWith(object, '[0][1]', _.constant('a'), Object);
// => { '0': { '1': 'a' } }

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) values(object) → {Array}

Creates an array of the own enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 0.1.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)

_.values('hi');
// => ['h', 'i']

(static) valuesIn(object) → {Array}

Creates an array of the own and inherited enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)

(static) valuesIn(object) → {Array}

Creates an array of the own and inherited enumerable string keyed property values of `object`. **Note:** Non-object values are coerced to objects.
Parameters:
Name Type Description
object Object The object to query.
Since:
  • 3.0.0
Source:
Returns:
Returns the array of property values.
Type
Array
Example
function Foo() {
  this.a = 1;
  this.b = 2;
}

Foo.prototype.c = 3;

_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)

(static) words(stringopt, patternopt) → {Array}

Splits `string` into an array of its words.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
pattern RegExp | string <optional>
The pattern to match words.
Since:
  • 3.0.0
Source:
Returns:
Returns the words of `string`.
Type
Array
Example
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']

_.words('fred, barney, & pebbles', /[^, ]+/g);
// => ['fred', 'barney', '&', 'pebbles']

(static) words(stringopt, patternopt) → {Array}

Splits `string` into an array of its words.
Parameters:
Name Type Attributes Default Description
string string <optional>
'' The string to inspect.
pattern RegExp | string <optional>
The pattern to match words.
Since:
  • 3.0.0
Source:
Returns:
Returns the words of `string`.
Type
Array
Example
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']

_.words('fred, barney, & pebbles', /[^, ]+/g);
// => ['fred', 'barney', '&', 'pebbles']

(static) wrap(value, wrapperopt) → {function}

Creates a function that provides `value` to `wrapper` as its first argument. Any additional arguments provided to the function are appended to those provided to the `wrapper`. The wrapper is invoked with the `this` binding of the created function.
Parameters:
Name Type Attributes Default Description
value * The value to wrap.
wrapper function <optional>
identity The wrapper function.
Since:
  • 0.1.0
Source:
Returns:
Returns the new function.
Type
function
Example
var p = _.wrap(_.escape, function(func, text) {
  return '<p>' + func(text) + '</p>';
});

p('fred, barney, & pebbles');
// => '<p>fred, barney, &amp; pebbles</p>'

(static) wrap(value, wrapperopt) → {function}

Creates a function that provides `value` to `wrapper` as its first argument. Any additional arguments provided to the function are appended to those provided to the `wrapper`. The wrapper is invoked with the `this` binding of the created function.
Parameters:
Name Type Attributes Default Description
value * The value to wrap.
wrapper function <optional>
identity The wrapper function.
Since:
  • 0.1.0
Source:
Returns:
Returns the new function.
Type
function
Example
var p = _.wrap(_.escape, function(func, text) {
  return '<p>' + func(text) + '</p>';
});

p('fred, barney, & pebbles');
// => '<p>fred, barney, &amp; pebbles</p>'

(static) zipObject(propsopt, valuesopt) → {Object}

This method is like `_.fromPairs` except that it accepts two arrays, one of property identifiers and one of corresponding values.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 0.4.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }

(static) zipObject(propsopt, valuesopt) → {Object}

This method is like `_.fromPairs` except that it accepts two arrays, one of property identifiers and one of corresponding values.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 0.4.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }

(static) zipObjectDeep(propsopt, valuesopt) → {Object}

This method is like `_.zipObject` except that it supports property paths.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 4.1.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }

(static) zipObjectDeep(propsopt, valuesopt) → {Object}

This method is like `_.zipObject` except that it supports property paths.
Parameters:
Name Type Attributes Default Description
props Array <optional>
[] The property identifiers.
values Array <optional>
[] The property values.
Since:
  • 4.1.0
Source:
Returns:
Returns the new object.
Type
Object
Example
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }